Stephen 'The Rifleman' Flemmi, center right, sits on the stand on Thursday.
Courtroom decorum in the James "Whitey" Bulger trial was shattered for a third time Thursday when Stephen "The Rifleman" Flemmi muttered an expletive while he stared down the accused gang boss from the witness box.
Booking photo of James 'Whitey' Bulger
Bulger had an inaudible retort for his one-time confederate, reporters in Boston Federal Court said.
The two men had not seen each other since 1994 when Bulger, now 83, went on the lam, leaving behind Flemmi, who is now 79 and serving a life sentence for 10 murders.
Flemmi's turn on the stand was expected to be a dramatic moment in a captivating trial — which has already seen Bulger curse at a corrupt former FBI agent and exchange unprintable oaths with former protege Kevin Weeks.
The appearance, though abbreviated, lived up to its billing.
As he was led into the witness box, Flemmi glared at Bulger, who merely glanced at him. The real sparks flew when Flemmi was done testifying and stood with his hands on his hips, eyes locked on Bulger.
Flemmi is on the witness stand, stares at Bulger, Bulger looks back. Yikes! #Bulger— Denise Lavoie (@deniselavoie_ap) July 18, 2013
Courtroom reporters tweeted that Flemmi uttered a profanity at the accused gang leader, who did not hold his tongue.
Stevie needs to have his mouth washed out with soap like Whitey and Kevin Weeks. He just said Robin Harris' favorite word to Whitey. #Bulger— Kevin Cullen (@GlobeCullen) July 18, 2013
Flemmi was on the stand for less than an hour, telling jurors how he met Bulger in 1969 and their relationship was "strictly criminal." Bulger, he said, was "overbearing, forceful."
In a moment that could have only enraged Bulger, who claims he was not an informant, Flemmi described how the Winter Hill Gang boss delivered information about mobsters and associates to his FBI handlers.
Flemmi also detailed how he pleaded guilty to extortion, money-laundering, perjury and 10 murders in a deal that allowed him him to escape the death penalty.
Flemmi is expected to give specifics of those murders when he returns to the stand on Friday.
The Associated Press contributed to this story.