This is the fourth and final part. Part three was posted on February 8, part two on February 7 and part one on February 6.
On August 20, 1940, Leon Trotsky was assassinated by Stalinist agent Ramón Mercader in the Mexico City suburb of Coyoacán. Mercader’s access to the great revolutionary was made possible through his relationship with Sylvia Ageloff, a member of the Socialist Workers Party (SWP). In the aftermath of the assassination, Ageloff presented herself as an innocent victim of Mercader’s duplicity, a claim that was never challenged by the SWP.
This series of articles constitutes the first systematic investigation by the Trotskyist movement of Ageloff’s role and continues the work of the International Committee of the Fourth International’s Security and the Fourth International investigation. It is published in four parts.
The Mexican investigation into the assassination
With the initial interviews of Ageloff and Jacson-Mornard, the Mexican investigation began in earnest.
The Trotsky assassination is still viewed in Mexico as the most important murder case in the country’s modern history. The Mexican government carried out the only serious contemporaneous investigation of the assassination. It included an examination of Ageloff’s role in the plot. Her self-serving alibis, fits of hysteria, and proclamations of innocence did not deter Mexican investigators from critically evaluating Ageloff’s actions on the basis of the facts.
The government of Lázaro Cárdenas and the Mexico City police viewed the investigation as a legal matter of utmost importance. The assassination of a high-profile refugee by foreign agents—especially one who commanded as much respect in the working class as Trotsky—was a challenge to the national sovereignty of Mexico. The government assigned its most prominent police investigators and public prosecutors to handle the case. Its investigation was objective and professional. Officials conducted dozens of interviews and employed advanced methods that are still taught to contemporary Mexican criminologists. Those responsible for the investigation, including famed Mexican criminologist Alfonso Quiroz Cuarón, demonstrated a level of concern over the assassination and its participants that was lacking in the SWP’s response. 
The Mexican investigators began by interviewing Ageloff and Jacson-Mornard. In the course of their preliminary investigation, prosecutors began to accumulate powerful circumstantial evidence they believed disproved her claim to innocence.
The Mexican preliminary investigation
When Ageloff began to respond to questions, the police and prosecutors had the opportunity to observe her behavior and compare her explanations of what transpired to Jacson-Mornard’s statements and the statements of other witnesses. Based on the information they had gathered about Ageloff’s background and her actions, they determined that her claim to have been duped was not believable.
The initial circumstantial evidence supporting this determination included the following:
- Mexican authorities believed that Ageloff’s role in arranging the dinner with Schüssler cast heavy suspicion upon her. They believed Ageloff and Jacson-Mornard made plans with the Schüsslers in order to ensure that Schüssler would remain absent from Trotsky’s compound, thereby facilitating the assassination.
- Ageloff admitted that she had family in Russia. This was seen to raise questions as to whether the GPU could apply pressure by threatening violence against those in Russia.
- Ageloff admitted that on one occasion she saw that “when [Mercader] wrote to his boss he did it in code.” She said she asked him about the code, “and then he made a number of code signs on a piece of paper, then broke it immediately.”  Prosecutors believed that if she had seen this, her failure to report it to Trotsky indicated involvement in the criminal conspiracy.
- Similarly, the investigation learned, “Sylvia affirmed that Jackson never permitted her to review his correspondence, which he kept under seal, and also when he came from New York to Mexico, Jackson never separated himself from a suitcase which he had in his hands.”  Ageloff’s failure to report these details to Trotsky also implied that she was involved in the plot but was attempting to create a backstory to present herself as innocent.
- To the prosecution, the fact that Jacson-Mornard proclaimed Ageloff’s innocence was further circumstantial evidence that the two were collaborating. During a hearing, Jacson-Mornard told the judge, “Having read and reread the text of the relative part of said order; I find that everything that the order says regarding Sylvia does not convince me; and that if I had been the judge, I would have released her.” 
- Prosecutor Francisco Cabeza de Vaca said Jacson-Mornard’s story—that he and Ageloff were in love and that the assassin killed Trotsky because he interfered in their relationship—was “absolutely absurd, what you have declared up to now is unacceptable, it would not work in the brain of any reasonable person nor in the brain of a child; we cannot accept nor will we accept it.”  Cabeza de Vaca said Jacson-Mornard “must recognize that this argument is completely despicable, that it is unacceptable, that common sense rejects it, and that for the last time I am giving you the opportunity to tell the truth.” 
Ageloff’s jobs and access to money
Police and prosecutors also learned in their investigation that Jacson-Mornard had provided Ageloff with a string of jobs in Paris and that he had given her thousands of dollars over the course of their purported relationship. The Mexican investigators established that Ageloff received only $103 monthly from her job as a child psychologist in New York, and, as Barrón Cruz noted, “obviously, authorities asked her about how she got the economic resources to keep making trips” to Europe and Mexico. 
According to Barrón Cruz, Cabeza de Vaca believed it was highly incriminating that “Sylvia mentioned that Jackson had given her $3,000 in New York and they deposited it in a bank on Broadway, which she couldn’t remember the name; in this respect, Jackson corrects her and says it was actually $3,500.”  Adjusted for inflation, $3,000 in 1940 equals roughly $55,000 today. Mexican police believed Ageloff spent this money as an espionage-related work expense to visit Jacson-Mornard in Mexico.
The FBI investigation
The Mexican investigators were not the only ones to draw conclusions about Ageloff’s responsibility in Trotsky’s assassination. The FBI conducted a separate investigation of its own and reached the same conclusions as the Mexicans.
In particular, the FBI viewed the transfer of $3,000 as highly probative evidence that she was a GPU agent.
In a September 5, 1940 FBI report, agent J.B. Little communicated the views of agent Raymond E. Murphy, who explained that in other Soviet espionage cases, GPU co-conspirators urged their partners “to deposit $3,000” on their behalf. “Mr. Murphy advised that the deposit of $3,000 on the part of these individuals seems to be uniform in connection with the operation of Russian agents, and he was calling this to the attention of the Bureau for its consideration.”  Ageloff claimed the $3,000 she received was “left him [Jacson-Mornard] by his mother when she died.” 
The FBI documents of the investigation listed both “Mornard” and “Ageloff” as accomplices in the crime. On August 29, 1940, the FBI reported on the results of its third interview with her. The report indicates that the FBI was applying pressure on Sylvia Ageloff and her family to encourage her to come clean and tell the truth, which the agents suspected Ageloff was hiding. The FBI was interested in learning what Ageloff knew about the internal functioning of the GPU. The report reads:
An interview was had with Monte Ageloff, brother of Sylvia Ageloff, and it was impressed upon him that his sister was really in trouble, and that the Mexican Authorities believed that she was shielding the assassin Jacson, and that they probably would consign her to the Penal Court as an accomplice, and that if he could have any influence over her, he should persuade her to tell the whole truth. The writer was present at the first interview between Monte and his sister, and heard him give her the advice that the writer had given him. Notwithstanding this advice, a subsequent interview with her develops that she is standing pat on the proposition that she had no idea that Jacson intended to commit the crime which he did, and she had no idea of who his accomplices might be. 
The report suggests that the “New York Office” of the FBI conduct an interview with Hilda Ageloff and the Rosmers, but there are no publicly available records of those interviews. Contradicting her claims to have been duped, the FBI agent’s report concluded: “While this girl is very adept in pulling hysterical fits at the proper time, she, in my opinion, is a tough customer and may never tell all she knows that might be useful in determining just what was behind Jacson’s killing of Trotsky.” 
Whittaker Chambers’ appraisal of the Ageloff family
In the aftermath of the assassination, the SWP solicited the opinion of Whittaker Chambers as to Ageloff’s role in the assassination.
Chambers had intimate knowledge of the workings of the GPU. From 1932 to 1938 he served as the leader of a group of underground GPU spies working within the US government. Chambers’ involvement in this network—known as the “Ware group” after the network’s founder, Harold Ware—gave him access to high-level information about the role of GPU agents in the US.
Fearful on account of the 1937 Stalinist assassinations of Ignace Reiss and his friend and fellow Stalinist Julia Stewart Poyntz, Chambers broke with the Communist Party around 1938 and went into hiding. In 1939, Chambers began giving information to the US government.
In 1948, Chambers became a household name when he testified before the House Un-American Activities Committee and listed the names of the Communist Party members who comprised the Ware Group. This included Alger Hiss, the State Department official who denied being a spy, but who was convicted in 1950 for perjury. Chambers became a prominent post-war neoconservative.
Soon after his break with the Communist Party, Chambers held a secret discussion with a leading SWP member to provide information to the Trotskyist movement. This discussion was transcribed by the SWP and known as the “W Memorandum.” Chambers’ conclusion about the Ageloff family was as follows:
Cannot believe innocence of Ageloff girls. Only a moron could live with GPU agent and not become cognizant. Present conduct of Sylvia not decisive in changing his mind; she may be trying to save herself, or remorseful (but not enough to tell all), or even playing a part. Any one of these three possibilities is more probable, he says, than is her innocence. Set-up of Ageloff household reminds him of scores of similar ones employed by GPU: two or three members of a family in the movement (which group in movement not important), while others have no connection with movement at all, but also serve GPU. When I said papa is in real estate, he laughed. He says that’s the traditional business. “GPU work runs in family dynasties.” And especially Jewish families in cities of large Jewish communities. Considers systematic combing of all phases of Ageloff family one of two main leads. 
The SWP took Chambers’ understanding of the dynamics of the GPU seriously. Otherwise, it would not have approached him to inquire about Sylvia Ageloff’s role. In response, Chambers gave the SWP a clear answer as to how Ageloff’s activity fit a pattern of GPU activity. He suggested how the party could begin to investigate the likelihood of a GPU “family dynasty,” and he made clear that his suspicions were not diminished by Ageloff’s hysterics, which he felt indicated she was acting. Least possible, he said, was that her conduct showed she was innocent.
Although the discussion with Chambers was confidential and intended for the purpose of facilitating the SWP’s own investigation of the assassination, Joseph Hansen divulged this valuable material to the State Department in September 1940, without the approval of the SWP. The FBI took Chambers’ suggestions seriously and expanded its investigation. In contrast, the SWP responded to Chambers’ information by refusing to conduct an investigation into Ageloff and her family’s ties to the GPU.
Mexican judge and prosecutor receive death threats
The criminal case in Mexico City was assigned to Judge Raúl Carrancá Trujillo in the Sixth Criminal Court of Coyoacán. Under Mexican criminal law in 1940, the decision to convict or acquit a defendant fell to the judge and not to a jury.
To the GPU, the arrest of Ageloff and Jacson-Mornard posed an immense risk of exposure. With the assassin in Mexican police custody, it would not be so easy to silence him as they had Sheldon Harte. The detention of Ageloff, a US citizen, complicated matters further by threatening the exposure of their US networks.
Judge Carrancá began receiving death threats from Stalinists, warning him not to expose the GPU network behind the crime. One such letter, now in the Mexican national archives, reads:
Whatever steps you take in the trial of Jacques Mornard for the murder of Trotsky that tend to make him declare that he is an agent of the GPU and therefore clarify an international issue of deep and serious importance, you will pay very dearly. Remember that the powerful action of an organization has infiltrated a home which was believed unbreachable. 
This threat itself admitted to a broader plot and confirmed that the GPU was responsible for infiltrating “a home which was believed unbreachable.” Another threat read: “Be very careful Raúl that very soon the GPU will put you in the trunk.”
Prosecutor Cabeza de Vaca received similar threats. Victor Serge noted that “Francisco Cabeza de Vaca had been threatened with assassination various times.”  Cabeza de Vaca’s grandson, Daniel Cabeza de Vaca (who was Attorney General of Mexico from 2005 to 2006), would later explain that the threats were specifically related to his decision to investigate Ageloff and that his grandfather was “threatened on various occasions for not allowing the liberation of Sylvia Ageloff.” 
Prosecutor demands Ageloff’s detention and charges her with murder
Despite these threats, when the preliminary investigation concluded, prosecutor Cabeza de Vaca charged both Ageloff and Mercader with murder. He demanded that they both be incarcerated pending the outcome of the criminal case.
His filing, written in a prosaic legal form peculiar to Mexican criminal procedure, developed the circumstantial evidence uncovered by the investigation and presented the following argument against Ageloff:
Although it’s true that Sylvia was not present during the aggression against Trotsky, it’s also true that, due to the series of circumstances laid out in these proceedings, there is a belief that said person was not unaware of the plans developed by Jackson or Mornard, since she knew about the previous attempts aimed against the now deceased, and in these circumstances Sylvia, who appears to have enjoyed the friendship and trust of the Trotsky family as shown by the actions, should have acted with suspicion and wariness having discovered that she could serve as a means, as it occurred, for her lover to enter the house … especially since Sylvia herself knew that Jackson had no background as a Marxist and much less as a member of the Fourth International … as she knew all the same that her repeated lover, now indicted, had changed his name, had no known job, had used a fake passport and had also provided addresses to her that were also false, with all of this indicating that the aforementioned Sylvia was not loyal to Leon Trotsky, since she failed to communicate her suspicions regarding her lover, and without being able to claim ignorance because she is an educated person who claims to hold a university degree. 
Ageloff’s attorneys opposed this motion, but Judge Carrancá granted the prosecutor’s request, agreed that Cabeza de Vaca’s arguments were correct, stated his disbelief of the argument that she could be innocent, and ordered both Ageloff and Jacson-Mornard detained.
This order was not a mere pre-trial formality. Barrón Cruz wrote that on August 31, “Judge Carrancá Trujillo decided to exercise a decree of formal prison against Frank Jacson and Sylvia Ageloff, finding sufficient proof for the crime of homicide to prove the responsibility of both (emphasis added).” 
The Mexican press widely reported Ageloff’s imprisonment. La Prensa wrote, “It was a great surprise when news was received that the judge had decreed formal prison” for Ageloff. 
Ageloff’s attorneys filed another motion to secure her freedom. Prosecutor Cabeza de Vaca then filed a response demanding she be held in prison pending the judge’s final decision as to the charge of murder. Cabeza de Vaca’s response to Ageloff’s attorneys—again written in the long Mexican legal format—summarized the Mexican case against Ageloff:
Due to the political milieu in which Mr. León Trotsky operated … none of the sympathizers and friends that visited him frequently avoided this person’s dangerous situation, being exposed at any moment of being a victim of new aggressions … in these conditions, those who referred to each other as friends of the deceased had an excessive distrust about analyzing each other regarding the safety of the deceased when dealing with them, and it’s logical to assume that a somewhat odd attitude of these friends would of course raise in others … a suspicion that couldn’t be quelled. … Sylvia Ageloff … knew that he [Jacques Mornard] had no background as a Marxist and much less as a supporter and member of the Fourth International; it’s not possible to assume that when the suspect moved from Europe to the Americas and changed his name to Frank Jackson, the strange impression that such an attitude must have caused on Sylvia was left unexplained by him. … Mornard’s falsehoods regarding the activities he claimed to be engaged in in the Americas, knowing these [must have] strengthened Sylvia’s suspicions regarding Mornard’s real purpose for living mysteriously … even more so, Sylvia could not have stopped demanding [of] her lover a satisfactory explanation after substantiating that he had sometimes not provided his real address in this city.
The excessive distrust of a loyal friend to Mr. Trotsky could not have remained silent when Sylvia saw her lover Mornard at the house of the deceased. … it’s impossible to assume that, had Sylvia been loyal to the deceased, she would not have communicated her suspicions to him regarding the real intentions of the suspect. If Sylvia herself accepts that she found Mornard’s attitude suspicious when he showed a keen interest in the destiny of two spies who were arrested. Why didn’t she apprise someone of her suspicions and warned the deceased of the danger posed by being in contact with someone behaving insincerely? How can it be explained that she kept being his lover?
There is only one logical explanation: Ageloff knew Mornard’s true intentions regarding the attempt of the 20th of this month. There is no reason at all to consider Sylvia a loyal friend of the deceased since it’s not demonstrated by the records that she carried out any action making such loyalty apparent. The fact that the female suspect now feigns great sorrow for Trotsky’s death and a deep hatred toward his killer should not give a positive impression at all on anyone judging her.
No explanation is possible for the fact that Sylvia could have lived and traveled comfortably from the United States to Mexico with a modest monthly salary of 124 dollars, without accepting money from Mornard, who used her in Mexico to accomplish the homicidal plans, with Sylvia knowing this situation. To prove that a previous understanding existed between Sylvia and Mornard regarding the actions he perpetrated, and which calls upon both of their detentions, it’s enough to mention that she came to Mexico:
1) in January of this year with the purpose of spending a short vacation and, nevertheless, stayed until March, a time that corresponds more or less to that when Mornard began visiting Mr. Trotsky’s house; 2) that on the day of the events both of the detainees invited Schüssler to dinner, most likely to keep him away from the house of the deceased; 3) the fact that Sylvia did not go with Mornard to the Coyoacán house on the twentieth of this month, an absence that favored Mornard’s plans and is unexplainable given the friendship that Ageloff enjoyed in that house; and 4) the trip planned by both on the day following that of the aggression. 
Despite the ongoing death threats against him, Judge Carrancá agreed with this filing and refused to order Ageloff’s release.
September 1940: Prosecutor prepares to charge Hilda Ageloff
According to the Brooklyn Daily Eagle, Ageloff’s father personally traveled to Mexico City to try to arrange his daughter’s release. The August 24, 1940 edition notes that Samuel Ageloff was “due to arrive today” and was “reported to have flown from Washington.” He also wrote to President Cárdenas and demanded the president intervene to release his daughter.
Less than two weeks later, the Daily Eagle reported that Ageloff’s attorneys feared that Hilda would also be arrested by Mexican authorities as an accomplice in the murder. The September 4, 1940 edition reads:
Defense attorneys for Miss Sylvia Ageloff, Brooklyn woman held for complicity in the murder of Leon Trotsky, today pressed a suit in the capital’s first criminal court for an injunction to prevent the arrest of her sister, Hilda, who arrived today by plane from New York. The attorneys explained the move was precautionary. … Miss Hilda Ageloff would be liable to detention as an accomplice should questioning of her disclose she ever entertained suspicions of Frank Jackson, her sister’s friend, charged with murder.
In November, with Sylvia Ageloff still detained pending the judge’s ruling on the charge of murder, Cabeza de Vaca threatened to arrest Hilda and expand the investigation into the Ageloff family. At this time, Samuel Ageloff issued public statements urging the US government to help secure Sylvia’s release.
On November 19, 1940, the Daily Eagle published an article titled “Ageloff Seeks US Aid to Release Daughter.” The article explained:
Samuel Ageloff of 76 Remsen St., whose daughter, Sylvia, is held in a Mexico City hospital on a charge of complicity in the pick-ax murder of Leon Trotsky, has appealed to Washington seeking State Department aid to obtain the release of his daughter, Alfred F. Ritter, attorney for the father, announced today.
December 1940: Ageloff is released from prison
The case placed tremendous pressure on the Mexican government, both from the United States and the Soviet Union. In December, apparently through diplomatic back channels, a deal was eventually worked out to secure Ageloff’s release without conviction.
It is not clear exactly how Ageloff’s release was secured. However, FBI reports imply that a deal had been arranged between high-level decision-makers. The FBI, which had few doubts about Ageloff’s guilt, believed she was more likely to tell them what she knew about the GPU’s internal operations if she did not face the likelihood that her admissions could be used to commit her to a lengthy murder sentence. That back channel discussions between the American and Mexican government on how best to deal with Ageloff were in progress is established by an FBI report, which stated:
It is understood confidentially that the girl will be held for possibly a week or two longer, and then be discharged by the Judge of the Court at Coyoacan, and will be allowed to return to the United States. It may be that further questioning of her in the United States might develop more than has been developed in the difficult questioning of her in Mexico (emphasis added). 
Cabeza de Vaca continued to advocate for Ageloff’s incarceration and prosecution for murder, convinced that he was uncovering a GPU network with deep ties within the US and Mexico.
But ultimately, Carrancá, yielding to high-level pressure, released her from prison and ruled she was not guilty of murder. In his short written decision, Carrancá said he based his ruling on the fact that “Jacson and Ageloff have always said that the aforementioned Sylvia did not take any part” in the assassination.  He provided no additional reasoning for his decision.
This was a political decision that lacked legal credibility. Carrancá and all those involved knew this rationale was without logical justification, because Jacson-Mornard was at that point lying about every element of his role in the assassination. Even his true name would not become known until 1950. Nevertheless, sufficient pressure was brought to bear that Ageloff was released. She returned to New York in December 1940.
December 1940: Sylvia Ageloff refuses to provide evidence against Jacson-Mornard
Back in New York City, members of the press asked Hilda Ageloff if Sylvia or any family members were prepared to testify against Jacson-Mornard, whose trial was still ongoing in Mexico City. Hilda’s response on her sister’s behalf was: “As far as we are concerned, the case is closed.” 
This reaction served the interests only of the Stalinists. A supporter of Trotsky would have urged an exposure of Jacson-Mornard’s true role. At the time, the GPU maintained it was not involved in Trotsky’s assassination and the international Stalinist press publicized Jacson-Mornard’s claim to be a disgruntled Trotskyist in order to discredit the Trotskyist movement. Had Sylvia Ageloff been merely an innocent victim, nobody would have been better positioned than her to help the investigation expose Jacson-Mornard’s GPU ties.
But to the Ageloffs, the case was closed. By refusing to provide information to the SWP or the authorities, Hilda and Sylvia were aiding Trotsky’s murderer and shielding the GPU.
December 1940: Sylvia Ageloff’s press release
Upon her return to New York City in December 1940, Sylvia Ageloff issued a press release through her father’s real estate office. It read:
I want to take this opportunity of straightening out some of the garbled reports printed in the papers. I never introduced Jacson to Leon Trotsky. This fact is clearly established by the evidence that has been gathered and can be corroborated by any one who wishes to take the trouble to do that.
Furthermore, the evidence and the testimony overwhelmingly established, as the judge himself stated in his verdict, that I was the victim of a chain of circumstances of which I was entirely ignorant and over which I had no control.
I was an admirer and personal friend of Mr. and Mrs. Leon Trotsky. I have no political affiliations.
My strongest desire now is to try to put what has happened into the past. I want to try to return to the life of an ordinary citizen. I am sorry I am too ill at the present time to give any personal interviews. 
Sylvia Ageloff was lying through her teeth. There was not a shred of truth in this statement.
There was nothing “garbled” in the newspaper reports referencing the fact that Mexican police and prosecutors charged her with Trotsky’s murder and accused her of being a GPU agent.
She did, in fact, introduce Trotsky to his future assassin. Ageloff arranged for Jacson-Mornard and Trotsky to meet face to face in August 1940, one week before the attack, when she brought him into the compound unannounced, surprising Sedova, who believed she had arranged to meet with only Sylvia. As a result of the discussion that took place with Trotsky on this date, Jacson-Mornard drafted the “article” that Trotsky was reviewing when the alpenstock crushed his skull.
Moreover, Ageloff falsely presented Jacson-Mornard to the Trotskys as her “husband” in the days before the assassination. Sedova would later state that the assassin was “received first and foremost as Sylvia’s husband.” Ageloff’s lie solidified Jacson-Mornard’s bona fides and enabled him to gain entry to the compound on the day of the attack. Moreover, this false claim of marriage was to become a central element of the assassin’s fictional motive for committing murder, i.e., that Trotsky had opposed his “marriage” to Ageloff.
Beyond the events immediately preceding the assassination, Ageloff’s statement that she did not introduce Jacson-Mornard to Trotsky was a gross cover-up of her role over the course of their two-year collaboration.
At each stage, Ageloff was the critical link, integrating Jacson-Mornard further and further into the Trotskyist movement and ultimately into Trotsky’s home. In the summer of 1938, she introduced him to the leadership of the international Trotskyist movement and brought him to the founding conference of the Fourth International, where she introduced him to the delegates. Ageloff introduced him to her friends in the SWP in New York in 1939, to the Rosmers in Mexico City in early 1940, brought him within the walls of the compound for the first time that March, and, it can be legitimately assumed, introduced him to the leaders of the SWP who traveled to Mexico City that June. She helped him evade US immigration officials when he came to meet his GPU handlers in New York that month and helped him evade detection again while reentering Mexico on his return trip to kill Trotsky.
Ageloff’s next claim—that Judge Carrancá affirmed that the evidence presented during the criminal proceedings in Mexico “overwhelmingly established” that she was “the victim of a chain of circumstances of which I was entirely ignorant and over which I had no control”—was also a lie.
The text of Judge Carrancá’s decision is now publicly available, and it makes no statements along these lines. Her claim that the criminal proceedings found her to be “entirely ignorant” of Jacson-Mornard’s true intentions was even belied by her own testimony, in which she acknowledged there were several instances when she said she was, in fact, alerted to Jacson-Mornard’s suspicious behavior. When under arrest, her claim was not that she was “entirely ignorant,” but that she overlooked the inconsistencies in his story because she was blinded by love. Back in the United States and beyond the jurisdiction of the Mexican authorities who were on to her, she could afford to protect herself by distancing herself even further from the truth.
Ageloff’s claim to have been merely “an admirer and personal friend of Mr. and Mrs. Trotsky” who has “no political affiliations” was another lie aimed at presenting herself as fortune’s fool. Everyone involved in the investigation, including the Mexican authorities, the FBI and the SWP, knew Ageloff had been active in socialist politics since 1934, that she was present at the 1938 founding conference of the Fourth International, and that she had been a member of the SWP. But the SWP never challenged these lies, and Ageloff faded out of the public eye.
April 1943: The GPU murders prosecutor Cabeza de Vaca
Francisco Cabeza de Vaca, Ageloff’s prosecutor, was not so fortunate. In April 1943, Jacson-Mornard was sentenced to 20 years in prison, retroactive to the date of the crime. Shortly after the sentencing hearing of Jacson-Mornard adjourned, Cabeza de Vaca walked out onto the street in central Coyoacán and, according to his family, was assassinated. Cabeza de Vaca’s grandson, Daniel Cabeza de Vaca, who is a prominent government attorney and served as Mexico’s attorney general from 2005 to 2006, wrote in the introduction to Barrón Cruz’s review of the investigation:
Among all the others who intervened in the investigation of the murder of Leon Trotsky, little or nothing has been publicly said about Francisco Cabeza de Vaca Acosta. Today his resurfacing is well merited. …
When we were children—my siblings, cousins and I—my grandmother would tell us with great feeling about our grandfather. In particular, she told us that we had to honor the inheritance of love for justice that had been given to us by a man who had died for this love. Relating an anecdote, but with reddened eyes, she would tell us that my grandfather had been threatened to stop the investigation which had demonstrated much sooner that which would later become known and recognized, and that now is history: the true identity of the killer and the responsibility of the Soviet GPU in the murder of Trotsky.
My grandmother referred to the murder of Trotsky as a conspiracy, and said the same assassins had murdered my grandfather. She would tell us how my grandfather said goodbye to her; he said that the same assassins of Trotsky had injected something in his skin when he left a restaurant in the center of Coyoacán, that they had poisoned him and that an antidote did not exist; he gave her copies of the case file and later died. Later they discovered the devices and the poison that the Stalinist assassins used.
In that time the only proof that my grandmother had were the copies of the investigation that he secretly had given her at his death, and the fact that she, at thirty years of age and with six children, had to leave her house in Coyoacán to take refuge with her family in the city of Leon, Guanajuato.” 
Daniel Cabeza de Vaca added:
Since the beginning of his complex labor as the man responsible for the investigation of Trotsky, he had the firm conviction that Ramón could not have acted alone, but that he worked and trained with a complex cover. Sadly he, my endearing grandfather, after being threatened on various occasions for not allowing the liberation of Sylvia Ageloff—the ex-girlfriend of Ramón who fatally allowed him to get close to Trotsky—died under suspicious circumstances, on exactly the same day that the sentence against Ramón was published, hours after being apparently punctured with a strange substance…
For all these reasons, it could well be that Sylvia’s case is similar or parallel to that of Robert Sheldon Harte, who was exculpated at the time by Trotsky himself, for his participation in the first attack against his life with David Alfaro Siqueiros and his brother in law Luis Arenal and others; because Robert, just like Sylvia, benefited from the closeness and confidence of Trotsky and his family. But as time showed, paradoxically, Robert in fact had acted on the orders of Leonid A. Eitington, chief of the NKVD in Spain, who had been the lover of Caridad [del Rio, Mercader’s mother] and later the boss of Sylvia and Ramón. 
The prosecutor’s grandson concluded: “In this sense, the opening of information and recently uncovered discoveries must serve to put forward new hypotheses about the real role played by Sylvia, as well as different people with whom she related.” 
December 1950: Ageloff testifies before the House Un-American Activities Committee
Ten years after the assassination, in December 1950, Hilda Ageloff, Sylvia Ageloff and Ruby Weil were subpoenaed and appeared before the House Un-American Activities Committee (HUAC). The hearing was titled “American Aspects of the Assassination of Leon Trotsky,” and the three women were called to testify as to their knowledge of the GPU’s role in preparing the assassination. 
HUAC was not interested in Trotsky’s assassination from the standpoint of punishing those responsible for murdering its revolutionary adversary. By 1950, US government investigators were keenly aware of the intersection, in terms of critical personnel, between the GPU operation to murder Trotsky and later war-time and post-World War II atomic spying. The only reason HUAC called Sylvia Ageloff as a witness was that it had reason to believe—or knew definitively—that she possessed significant information about Soviet espionage in the United States.
The December hearing, the last of four hearings investigating “American Aspects of the Assassination of Leon Trotsky,” took place after HUAC had held three hearings about American Communist Party involvement in a failed plot to launder money to Mexico to secure Jacson-Mornard’s release from a Mexican prison. Aside from the Ageloffs and Weil, eight other suspected GPU agents testified publicly as part of the investigation.
Six months before the hearing, in June 1950, the publishing company Harper and Brothers released Louis Budenz’ second book, Men Without Faces, which pointed to the existence of a far broader GPU network. Budenz said that a GPU agent named “Helen” was working within the SWP, and he described how he had recruited Ruby Weil to become a GPU agent, sending her to Europe, where she and Sylvia Ageloff would meet Mornard-Jacson.
Three weeks before the December 1950 hearing with the Ageloffs, HUAC placed an affidavit submitted by Budenz on the record. The affidavit included specific details of the GPU agents with whom he had worked in infiltrating the Trotskyist movement and organizing Trotsky’s assassination. For the first time, Budenz named “Helen” by name. She was Sylvia Franklin (née Callen), James P. Cannon’s secretary. He also referenced that while in the Communist Party, he had “a number of agents for the Stalinist group planted in the Trotskyite camp.” 
Budenz explained that there were many more people he was prepared to publicly name as GPU agents if the need arose. “There was also a great number of people, in addition to those mentioned, whom I introduced” to GPU ringleader Dr. Gregory Rabinowitz, he wrote.  The last sentence of his affidavit read: “Should other details be required on this Trotskyite case, and there are a number which I have not covered, I always hold myself in readiness to be of such service to Congress as I can.” 
It was in this context that Sylvia Ageloff testified before HUAC. The actual hearing on December 4, 1950 lasted only 75 minutes, from 11 a.m. to 12:15 p.m. The hearing itself was preceded by repeated interviews between those called to testify and US government investigators. As Ruby Weil acknowledged, before testifying at the hearing she had “told this story several times to Government people.” 
The transcript of Sylvia Ageloff’s testimony is only six pages long. She was handled with the courtly respect that congressmen and staff attorneys reserved for former agents who had become informers. They politely chose not to mention that Ageloff had been arrested and charged with Trotsky’s murder in Mexico.
Ageloff testified that her 1938 voyage to Europe was “just a pleasure trip.”  When she met Jacson-Mornard, she said, “in the first place, I didn’t tell him I was a Trotskyite.”  Ageloff told the committee that she had no “first-hand information” as to how the assassin gained access to Trotsky’s home.  She said she had no indication that Jacson-Mornard was a GPU agent. 
She was asked by a committee staff attorney: “Did you feel in any way you had been involuntarily or unknowingly involved in this?” She replied: “I was involved insofar that I suppose if I had never met him, I guess he wouldn’t have gained entrance to the house at all. I should say for the record, though, that I never brought him to the house. … Mrs. Trotsky confirmed that.”  When asked, “Did you work for Leon Trotsky in Mexico City?” she replied: “No. I went to visit him. I was there once for exactly a half hour.”  Hilda Ageloff’s testimony conformed to the version told by Sylvia.
HUAC knew these statements were false, and Ageloff was evidently not concerned that she would be charged with perjury for lying under oath. The Mexican trial and the FBI’s own contemporaneous investigation had established that Ageloff had introduced Jacson-Mornard to all of her friends in the Trotskyist movement, that she visited the Trotsky house not once, but on multiple occasions between January and March 1940 and between August 9 and August 20. Additionally, she had brought Jacson-Mornard into the compound at the end of March, before she returned to the United States, and again when she returned to Mexico City in August.
Significantly, during her testimony Ageloff twice used the derogatory term “Trotskyite,” a term used by the Stalinists. Because of its association with mass murder and frame-ups, it was a term those associated with the Trotskyist movement would never employ.
After her testimony was completed, HUAC published an official summary of the testimony:
With reference to the testimony of the Ageloff sisters, it is pointed out that, as a result of their names being mentioned in connection with this matter by other sources, they have suffered hardships. The committee would like to state in their behalf that they cooperated fully with the committee and furnished valuable information during this particular investigation, despite the personal risk involved by their doing. 
The “other sources” referenced in the summary were the other GPU agents whom the government interviewed during its investigation. The record shows that this included ex-GPU recruiter Louis Budenz and several GPU agents involved in attempting to break Jacson-Mornard out of prison in Mexico City. It most likely also included some of the agents whom Budenz had fingered. If the committee spoke to Whittaker Chambers, which was likely given his consistent collaboration with HUAC, he would have told them his opinion that Sylvia Ageloff was an agent. These sources had “mentioned” the Ageloff sisters’ names “in connection with this matter.” In other words, multiple GPU agents were telling HUAC that Sylvia Ageloff was herself a GPU agent who was involved in carrying out Trotsky’s murder.
The summary also stated that Ageloff “cooperated fully” and “furnished valuable information” to the committee. Information would be valuable only insofar as it advanced the express purpose of the committee’s investigation, which was to uncover the GPU agents involved in plotting Trotsky’s assassination. Her December 4, 1950 testimony could not have been valuable to the government, because it was only a repetition of her well-known claim to have fallen in love with Jacson-Mornard, who remained imprisoned in Mexico. The valuable information she furnished must have been provided in private, and it must have included the names of GPU agents she knew.
The committee’s summary also references the “personal risk” the sisters confronted as a result of their collaboration with the US government. This could not have been a reference to the SWP, which evinced no interest in unmasking the Stalinist agents operating in their midst and failed to report on the hearing in the party press. The only reasonable explanation is that HUAC was referencing the “personal risk” the Ageloff sisters might face from the GPU.
In the years that followed Ageloff’s testimony, the government used the information it acquired in these early investigations to prosecute many GPU agents who had been engaged in “anti-Trotskyist” activities in the 1930s and 1940s. The US government became interested in those agents when they switched from anti-Trotskyist espionage to military and atomic spying after Trotsky’s assassination. Jack Soble was arrested in 1957, Mark Zborowski in 1958, and Soble’s brother Robert Soblen in 1960. James P. Cannon’s secretary, Sylvia Franklin (née Callen), and SWP member Floyd Cleveland Miller were named as unindicted co-conspirators in the prosecution of Soblen.
When these trials took place, just 20 years had passed since Trotsky’s assassination. Although the prosecution and guilty verdicts confirmed that high-level members of the Trotskyist movement had been GPU agents, the trials and their outcome were not reported in the press of the Socialist Workers Party. The FBI was conducting investigations, but the SWP was not.
Twenty-six years later, the FBI and J. Edgar Hoover continued to closely monitor discussion on Ageloff's complicity. On October 17, 1966, Hoover received a letter from an individual whose name is redacted in subsequently-released FBI files. The individual references Isaac Don Levine's book Mind of an Assassin and asks:
Can you perhaps inform me why the two American girls who were instrumental in making it possible for the convicted murderer to gain entrance into the Leon Trotsky home in Mexico City were never requested by the Mexican government for extradition and trial in that country? The book makes no mention of this. To what extent are these accessories to the murder liable at all, either here or in Mexico?
Hoover personally responded on October 20, 1966:
With respect to your inquiry, the matter to which you referred was not a violation within the investigative jurisdiction of the FBI, and I am therefore unable to comment in the manner your desire. Inasmuch as the murder of Leon Trotsky occurred in Mexico, any prosecution of individuals involved would have to be initiated by the authorities of that country.
In this answer, Hoover withheld the fact that Sylvia Ageloff was prosecuted by the authorities in Mexico, and that the prosecution wanted to charge Hilda Ageloff as well. Hoover's omission appears to have been aimed at blocking the inquirer from learning how the Ageloff sisters' release was secured.
The fate of Ramón Mercader and Sylvia Ageloff
Ramón Mercader was released from prison in Mexico in May 1960. He was placed in the custody of Czech diplomats and transported to the Soviet Union by way of Cuba, where the assassin was given a hero’s welcome at the Havana airport by the petty-bourgeois guerilla leader and virulent anti-Trotskyist, Che Guevara.
In January 1977, the International Committee of the Fourth International published information, based on research conducted in Mexico by David North and Alex Mitchell (then-editor of the News Line, published by the British Workers Revolutionary Party), establishing, based on correspondence between Mercader and his lawyer, Eduardo Ceniceros, that Mercader was in the Soviet Union on a vacation in the Donetsk region of Ukraine.
While he was living in the Soviet Union, the Stalinist bureaucracy awarded him the country’s highest honor, the Order of Lenin, and housed him in a comfortable apartment where he was in regular contact with the exiled leadership of the Spanish Communist Party. He traveled back and forth between the Soviet Union and Cuba, where he was an honored guest and personal acquaintance of Fidel Castro. He died in Cuba in 1978 at the age of 65.
Sylvia Ageloff lived a comfortable life in New York City and died in 1995 at the age of 86, having outlived the events in Coyoacán by more than a half century.
In 2011, her close friend Lillian Pollak was interviewed in her apartment on the Upper West Side of Manhattan. Sylvia Ageloff “lived very close to here,” she said, “in a beautiful apartment.”  Distant relatives of the Ageloff sisters said they never heard anything about the sisters through their own family, and that the only information they could ever ascertain about their lives was through public obituary notices.  According to the FBI, Sylvia operated a kindergarten in suburban New York and, after she provided the US government with “valuable information” about the GPU, faced no major inconveniences over her role in Trotsky’s assassination.
Based on all the information that is now available, it is possible to replace the myth of “poor little Sylvia” with an accurate account of her role in the political catastrophe of August 20, 1940. The real person finally takes the place of the constructed persona.
Who was Sylvia Ageloff? The evidence leads overwhelmingly to the conclusion that she was an agent of the GPU who played a critical role in the assassination of Leon Trotsky.
[Original sources not shown are available in part one, part two or part three.]
 It was as a result of the investigation conducted by the Mexican investigator Alfonso Quiroz Cuarón that Mercader’s true name became known to the public in 1949 or 1950.
 Barrón Cruz, p. 59.
 Ibid., p. 76.
 Ibid., p. 83.
 Ibid., p. 60.
 Ibid., p. 61.
 Ibid., p. 54.
 Ibid., p. 76.
 September 5, 1940 FBI report “Re: Murder of Trotsky in Mexico,” sent by JB Little to HH Clegg.
 New York Times, August 22, 1940, “Trotsky Dies of His Wounds; Asks Revolution Go Forward.”
 August 29, 1940 FBI Memorandum re: “Murder of Leon Trotsky.”
 Ibid. In a 1977 interview with David North conducted as part of the Security and the Fourth International investigation, FBI agent M.R. Griffin, who was actively involved in the investigation of the Stalinists involved in the assassination, said he believed that Ageloff was a GPU agent.
 The Gelfand Case, Volume I (Detroit: Labor Publications, 1985), p. 15.
 Luri, pp. 259–60.
 Ibid., p. 280.
 Barrón Cruz, p. xix.
 Ibid., p. 67.
 Ibid., p. 77.
 Ibid., p. 82.
 Ibid., pp. 83–85.
 August 29, 1940 FBI Memorandum re: “Murder of Leon Trotsky.”
 Barrón Cruz, p. 179.
 Luri, p. 272.
 Eric Gurevitch, “Thinking with Sylvia Ageloff,” Hypocrite Reader, August 2015. Available here.
 Barrón Cruz, pp. xiv–xv.
 Ibid., pp. xix–xx.
 Ruth Ageloff was also subpoenaed, but according to a committee staff attorney, she was ill. The committee decided not to require she submit evidence on the record and under oath.
 Ibid., p. vi.
 Ibid., p. ix.
 American Aspects of the Assassination of Leon Trotsky, US House of Representatives Committee on Un-American Activities, 1950, p. 3,416.
 Ibid., p. 3,402.
 Ibid., p. 3,403.
 Ibid., p. 3,404.
 Ibid, p. 3,406.
 Ibid., p. xiv.
 See note 51. Available here, pp. 15–16.
 Interview with Amy Feld by Eric London, August 17, 2020; interview with Eric M. Gurevitch by Eric London, August 17, 2020.