At times during his testimony on Monday, Stephen Flemmi mixed up names, forgot who was in attendance at meetings and was sometimes just confused by the questioning.
Flemmi, 79, was on the witness stand for a third day to provide testimony against his former crime partner James "Whitey" Bulger.
At one point, Assistant U.S. Attorney Fred Wyshak showed Flemmi an FBI informant report and asked him who the Winter Hill Gang was trying to falsely blame for a murder. Flemmi stared at the document for a moment and gave the name of the murder victim: John Callahan.
"How do you put the heat on John Callahan if you're going to kill him," Wyshak asked Flemmi.
"I get a little confused here, you know," Flemmi said.
Earlier in his testimony, Flemmi inadvertently caused a commotion when he suggested that Steve Davis, the brother of murder victim Debra Davis, was a drug dealer and law enforcement informant.
Davis, who has been in court every day for the trial, stood up and shouted, "You're a f—ing liar."
Wyshak had asked Flemmi to clarify, and Flemmi said he misspoke and meant Davis' brother Mickey. Flemmi then apologized for the mistake.
Flemmi will be on the stand again Tuesday.
Follow Michael Naughton on Twitter @metrobosmike.