Boston (CNN) -- A juror wept Friday as James "Whitey" Bulger's former partner told a tragic tale of a slip of the lip and the ensuing result -- the strangling death of a 26-year-old woman, who was killed because she'd heard too much.
What made this recitation of deadly details different from the ones that preceded it during reputed mob boss Bulger's trial in federal court was that the victim had been the girlfriend of the witness.
"It's affected me and it's going to affect me until the day I die," Stephen "The Rifleman" Flemmi said in the first humanizing testimony the jury had heard in two days of recollections about multiple murders and extortions.
Flemmi was Bulger's number-two front man for nearly two decades, when prosecutors say Bulger reigned terror over Boston. Bulger is charged with 19 killings in a 32-count indictment that includes extortion, money laundering, and racketeering in addition to the deaths.
"He strangled her all the way down to the basement...when he got to the basement she was dead," Flemmi told the jury, referring to Bulger and Flemmi's girlfriend, Debra Davis.
A female juror covered her mouth and began shaking, wiping away tears while she repeatedly checked the time, as if longing for the testimony to end.
Prosecutors brought up the horrific murder of Davis in 1981 just 10 minutes before court ended Friday.
In his testimony, Flemmi said his much younger girlfriend became very upset when he left her birthday party abruptly to meet with Bulger. Flemmi said he "inadvertently blurted out" to Davis that he and Bulger were FBI informants.
"I bit my tongue and said we have a connection to John Connolly in the FBI and I got to leave," Flemmi said, referring to his and Bulger's rogue FBI informant-handler. Connolly is serving a 40 year sentence in Florida on murder charges connected to information he leaked to Bulger.
Bulger then said several times that "he wanted to kill her" because of what Davis then knew about the duo's relationship with Connolly, Flemmi testified.
"I said no, of course not," Flemmi continued. "And he (Bulger) explained a whole litany of reasons why John Connolly helped us... all of us and (said) 'You are jeopardizing that.'"
Flemmi, who testified earlier that Connolly had tipped them off to indictments, wire taps, and investigations, said it took him a while to come around but he eventually agreed to the slaying of Davis.
"I couldn't do it...(Bulger) knew it ... he said, 'I'll take care of it, I'll do it,'" Flemmi told the jurors as they listened intently.
Flemmi invited Davis to a house he had just bought for his parents, and when they walked in the front door, "He (Bulger) grabbed her by the throat and strangled her," Flemmi said.
Prosecting attornery Fred Wyshak asked: "What did you do?"
Wyshak: "Why not?"
Flemmi: "That was the plan."
At that moment in court, Bulger -- whose attorneys made it very clear in opening statements that he does not want the death of women on his hands -- stared at his former partner for the first time all day. It was only for a few seconds before he turned his head back downward.
The two, who sparred with expletives at the end of court Thursday, virtually ignored each other Friday except for that one interlude.
"I wrapped her up and he (Bulger) went back upstairs" Flemmi went on.
Flemmi testified that he "cleaned up" and they proceeded to take Davis' body to an area near the Neponset river where they buried her in a shallow grave.
The remains of Debra Davis were excavated from a tidal marsh in late 2000. Most of her remains were discovered in plastic bags along with rope around the bags, a Massachusetts state forensic anthropologist testified last week.
Almost all of Davis' bones were recovered, according to Dr. Ann Marie Mires. Because her body was in bags, even some of her hair was preserved. The hair, along with pieces of bones, were tested for DNA and were positively identified as the remains of Davis, according to Mires.
Davis' brother, Steve Davis, has been a regular at trial since it began in June. He told reporters after court, "I've heard it before. It brings tears to my eyes but I learned how to deal and fight it, because I need to learn more about it, 'cause you don't know all it yet."
Flemmi pleaded guilty to 10 murders after charges were brought in 2004 and was spared the death penalty after agreeing to testify against Bulger.
Of his relationship with Davis, he told the jury: "I loved her, but I wasn't in love with her."
After court, the attorneys discussed the defense's amended witness list which had been reduced to 30 on Tuesday, from originally over 80 witnesses. Prosecuting attorney Brian Kelly argued that at least 15 of the witnesses -- former FBI agents -- would be a "waste" of the jury's time, as they are being called to refute the notion that Bulger was an informant, something Bulger has strongly denied. Kelly called these witnesses "irrelevant."
Defense attorney Hank Brennan responded: "Our witnesses are now down to 30. They are relevant to our case and we intend to call them."
The defense had mentioned on Tuesday that it would shrink its list if alleged extortion victim Stephen Rakes didn't testify because several defense witnesses were intended to challenge Rakes' expected testimony.
Rakes learned Tuesday that prosecutors no longer planned to call him to the stand, according to a friend of Rakes. On Wednesday, Rakes' body was discovered near a walking trail about 30 miles from his home.
CNN affiliate WBZ reported that his car was found Friday about six miles from where his remains were found.
Federal law enforcement authorities were "shocked" to learn about the unexplained death of Rakes, according to a source familiar with the investigation into Rakes' death. Authorities consider Rakes' death suspicious, the source added, and authorities hope that there is no connection to the ongoing Bulger trial.
The death is under investigation.
CNN's Laura Batchelor and Deborah Feyerick contributed to this report.