Bulger is accused of 19 killings and 13 counts of extortion and money-laundering in a 20-year "reign of terror" that defined South Boston from the early 1970s through 1995, CNN reported.
Defense attorney J.W. Carney summed up his case by questioning the credibility of prosecution witnesses, some who came to court with extensive criminal references, and worked out deals with the government for their testimony.
Carney accused the government of buying the testimony of those witnesses.
Prosecutors told the jury Bulger was an FBI informant who used protection from rogue agents to continue his life of crime.
Prosecuting attorney Fred Wyshak called Bulger one of the most "vicious, violent and calculating criminals to ever walk the streets of Boston."
"It doesn't matter if he is an informant or not," Wyshak told jurors. "It doesn't matter whether or not the FBI is leaking information to him."
Bulger was arrested by FBI agents in California in 2011.