James Hosty was born in 1928. He graduated with science degree in business administration from the University of Notre Dame in 1948.
Hosty worked for the First National Bank in Chicago and as a salesman before joining the Federal Bureau of Investigation in January, 1952. He initially was sent to Louisville but in December, 1953, was transferred to Dallas, Texas.
In March, 1963, Hosty was ordered to keep Lee Harvey Oswald under observation. Soon afterwards Hosty discovered that Oswald was purchasing The Worker, the newspaper of the American Communist Party. In June, Hosty heard from FBI headquarters that Oswald was in New Orleans, and requested information on him.
Hosty visited the home of Ruth Paine to discover where Oswald was living. He spoke to both Paine and Marina Oswald about Oswald. When Oswald heard about the visit he went to the FBI office in Dallas. When told that Hosty was at lunch Oswald left him a message in an envelope.
The contents of the envelope has remained a mystery. A receptionist working at the Dallas office claimed it included a threat to "blow up the FBI and the Dallas Police Department if you don't stop bothering my wife." Hosty later claimed it said: "If you have anything you want to learn about me, come talk to me directly. If you don't cease bothering my wife, I will take appropriate action and report this to the proper authorities."
Soon after Lee Harvey Oswald was arrested for the assassination of President John F. Kennedy, Hosty was called into the office of his superior, Gordon Shanklin. Hosty was asked about what he knew about Oswald. When Oswald was shot dead by Jack Ruby two days later, Shanklin ordered Hosty to destroy Oswald's letter.
The Federal Bureau of Investigation I discovered that Hosty's name and phone number appeared in Oswald's address book. J. Edgar Hoover was worried that this indicated that Oswald had been working closely with the FBI. That he might have been an FBI informant on the activities of left-wing groups such as the Fair Play for Cuba Committee. Instead of passing Oswald's address book to the Warren Commission, the FBI provided a typewritten transcription of the document in which the Hosty entry was omitted. When it was discovered that Hosty had misled the Warren Commission he was suspended from duty. Later he was transferred to the FBI office in Kansas City.
The message that Oswald handed in to the FBI office in Dallas remained a secret until 1975. It became public knowledge when someone in the FBI tipped off a journalist about the existence of Oswald's letter. Oswald's relationship with Hosty was explored by the Select Committee on Intelligence Activities and the Select Committee on Assassinations. Hosty admitted that he had misled the Warren Commission by not telling them about the existence of the letter from Oswald. Gordon Shanklin denied knowing about the letter but this evidence was contradicted by the testimony of Hosty and William Sullivan, the Assistant Director of the FBI.
Hosty worked for the FBI until his mandatory retirement at the age 55, in 1979. According to his son, Thomas Hosty, he granted interviews to anyone who wanted to talk about the case: "Even the ones who had some conspiracy agenda... He figured if these people met him, they would see who he was - a straight arrow.”
Hosty published his book on the Kennedy assassination, Assignment: Oswald in 1996. The New York Times has pointed out that: "In his memoir, Mr. Hosty acknowledges some mistakes but contends that F.B.I. officials made bigger errors - first by trying to eliminate evidence that might make it seem as though the agency had any hint of Oswald’s plans, and then by letting commission investigators portray Mr. Hosty as a bumbler when the evidence emerged about his contact with Oswald in the weeks before the assassination."
His son, Thomas Hosty, who helped him write the book, later recalled how upset his father had been by the suggestions that he was in some way involved in the conspiracy against John F. Kennedy: “The irony was, my dad was a devout Irish-Catholic Democrat Kennedy supporter... Being portrayed as part of a plot to kill the president, it was just so hurtful to him.”