BOSTON - A former FBI agent accused of lying during Boston gangster James "Whitey" Bulger's trial is expected to plead guilty to perjury charges.

Robert Fitzpatrick is slated to appear Monday afternoon in U.S. District Court in Boston for a change-of-plea hearing.

The now-76-year-old is accused of lying to jurors and overstating his professional accomplishments during Bulger's 2013 racketeering trial.

Fitzpatrick, who had been second-in-command of the FBI's Boston division during Bulger's bloody reign in Boston, was the first witness Bulger's lawyers called during the high-profile trial.

Prosecutors say Fitzpatrick falsely claimed to be the first officer who recovered the rifle used to assassinate Martin Luther King Jr. in 1968.

During the 2013 trial, Assistant U.S. Attorney Brian Kelly pressed Fitzpatrick about that claim.

"Isn't it true that three Memphis police officers found the rifle that was used to kill Martin Luther King, not Bob Fitzpatrick?" Kelly asked.

"I found the rifle along with them," Fitzpatrick replied. "They could have been there ... but I'm the one that took the rifle."

Prosecutors also suggested that Fitzpatrick exaggerated claims he tried to persuade supervisors to terminate Bulger as an informant because he didn't appear to be gathering information on the Mafia. They suggested he was just trying to sell copies of a book he wrote about Bulger.

Fitzpatrick originally pleaded not guilty last April to six counts each of perjury and obstruction of justice.

Bulger was convicted of a range of gangland crimes in the 1970s and '80s, including roles in 11 murders. He's currently serving two life sentences.