The girlfriend, Debra Davis, was about to leave him for another man. The defense recalled Martorano, who testified that Flemmi admitted he "accidentally strangled" the 26-year-old woman.
Flemmi acknowledged he lured Davis to a home but says Bulger strangled her because she was talking too much and had become a liability.
Wyshak recalled testimony that Bulger always needed to take a nap after strangling or shooting his victims to death.
In his closing argument, prosecutor Wyshak told the jurors they "don't have to decide who strangled Debbie Davis."
"He doesn't need to be the one that strangled her to be criminally liable," he said. "If he is a co-conspirator or he aids and abets, he is just as liable as he is if he puts his hands around her neck and strangles the life out of her."
A number of retired FBI agents and supervisors also took the stand, many testifying that they believed Bulger should have been shut down as an informant because he wasn't providing any useful information.
The agents said they never pressed the issue because apparently FBI headquarters felt Bulger was useful in taking down the New England Mafia.
There are 18 jurors,12 with six alternates. Eleven are men and seven are women.