'A cast of characters': Prosecution rests its case in Whitey Bulger trial

This courtroom sketch depicts James "Whitey" Bulger at the beginning of jury selection for his trial in U.S. District Court in Boston, on June 4. Bulger faces a long list of crimes, including playing a role in 19 killings. Margaret Small / AP file

The prosecution rested in the trial of James “Whitey” Bulger on Friday after seven weeks of testimony from the former head of the Winter Hill Gang’s ex-compatriots and alleged victims.

The defense for Bulger, 83, could begin to present its case as early as Monday at a federal courthouse in Boston, and is set to call up to 16 witnesses.

Bulger is accused of terrorizing South Boston for decades before spending 16 years on the run, evading FBI agents until he was arrested in Santa Monica, Calif., in 2011. He is on trial on federal charges of racketeering and the murder of 19 people.

The prosecution's witness list was peppered with alleged victims of Bulger's extortion and strong-arming and a host of confederates with gangland nicknames such as "The Rifleman" and "The Executioner." The trial so far has been full of witness-stand revelations and sometimes inconsistent testimony, said Chris Dearborn, a professor at Suffolk University, all of which the defense will likely try to pick apart in the coming week.

“This has been quite a cast of characters,” Dearborn said.

The defense is expected to take far less time than the prosecution in presenting their case, said Gerard T. Leone, a former prosecutor and partner at Nixon Peabody.

“I think they’re going to continue to try to develop their three themes that they opened with, which is Number One, that Whitey Bulger is not an informant; Number Two, that he was provided with some type of immunity; and Three, that he did not kill the females,” Leone said.

That will include attempting to chip away at the credibility of three former Bulger associates and star government witnesses: Stephen “The Rifleman” Flemmi, John “The Executioner” Martorano and Kevin Weeks.

“You’ve got to hammer the big three witnesses. You have to hammer those because they’re the most damaging in some respects,” Leone said.

On Thursday, Flemmi wound up nearly a week of testimony. Flemmi, who is serving a life sentence for 10 murders, recounted details of several killings that Bulger was allegedly involved in, and on Tuesday accused his former boss of having a relationship with a 16-year-old girl who he took to Mexico.

"You want to talk about pedophilia, right over there at that table," Flemmi said while pointing at Bulger, according to Reuters.

Another witness, Richard Buccheri, told the court on Thursday that Bulger threatened him with a shotgun in the 1980s, one of several tales of alleged extortion in the course of the trial.

“He slammed the table. Then he takes a shotgun that was on the table and sticks it in my mouth,” Buccheri said, according to Reuters. “He said he wanted 200 … he meant $200 thousand.”

Buccheri, a real estate developer, testified that Bulger then pulled the shotgun from his mouth and pressed a handgun against his head.

“He said, ‘If you don’t pay me in 30 days I’m going to kill you and your family,’” Buccheri testified. “I agreed to pay.”

Bulger has pleaded not guilty to a federal indictment that includes 19 murders, among other crimes. Prosecutors have said that Bulger was an FBI informant, an accusation that the aging gangster has vehemently denied.

His defense team did its best to attack Flemmi’s credibility on cross examination. Attorney Henry Brennan asked Flemmi whether he expected a reduced sentence for his sometimes gory testimony, which included an account of the strangling death of Deborah Hussey.

“I don’t know what the future holds,” Flemmi responded, according to Reuters. “Everybody hopes that at some point in the future something beneficial will happen to him. I’m still alive and that’s the hope.”

The big remaining question, Leone said, is whether Bulger himself will take the stand – something he might be tempted to do to salvage whatever might remain of his tough-guy legacy in the neighborhood he once ruled.

“Martorano, Weeks, and especially Flemmi, they really in some ways, it’s not a legal onus, but they’ve put the messaging onus back on Bulger,” Leone said.

NBC News’ Tracy Connor and Reuters contributed to this report.