In September 2008, word on the street was that Marcellus "Ant North" Jones had shot and killed Tyrek Taylor, his sometime sidekick in crime.

So when Jones walked into a family gathering at his aunt's house in Germantown that month, he was greeted by a passel of curious cousins who wanted to know why he killed "Reek."

Jones' alleged response - that Taylor wouldn't stop talking about how Jones had killed Beau Zabel three months earlier - did not stay in the family.

Listening quietly in the marijuana-steeped haze was Bruce Mattox, longtime boyfriend of Jones' younger sister, Tiffany. That information would come in handy five years later, after Mattox and his girlfriend had been arrested on charges of trashing their apartment. The couple decided to tell homicide detectives what they had heard in the hope of getting their cases dismissed.

On Thursday, both were on the witness stand for the prosecution in Marcellus Jones' murder trial in the June 15, 2008, slaying of Zabel during a robbery. The 23-year-old aspiring teacher from Minnesota was killed about 1:30 a.m. on the 800 block of Ellsworth Street in South Philadelphia.

Mattox, 30, confirmed his 2013 statement to detectives about what he said he heard that night at the Germantown house party.

"I really wasn't going to get involved, but then I thought it was as good a time as any if I wanted to get out of jail," Mattox told Assistant District Attorney Jacqueline Juliano Coelho.

Mattox said the two killings - Zabel's and Taylor's - also made him recall his family's pain when his sister was killed: "Somebody's lost a kid. Somebody's gone."

Defense attorney Richard J. Giuliani verbally sparred with Mattox about his motivation for testifying against Jones. Giuliani noted that Mattox's sister died in 1996, long before he and his girlfriend were arrested, and that he never mentioned her when he first spoke with homicide detectives.

"The reason you went to police is because you were looking out for you, wasn't it?" Giuliani asked.

"Yes," Mattox acknowledged. But he insisted that after making his statement, he chose not to recant because of the effect of his sister's death.

Referring to Zabel's parents and sister, sitting in the gallery, Mattox said, "They deserved some kind of closure."

Mattox said he could not explain why his girlfriend would recant her statement about her brother's incriminating comments. Indeed, Tiffany Jones' time on the witness stand was a complete contrast.

Sobbing heavily, the 34-year-old admitted implicating her brother in the two slayings but said she had made it up.

"It's all a lie, and that's the God's honest truth," she said.

Questioned by Coelho, Tiffany Jones denied being at her aunt's house that year, and insisted Mattox never met her brother and was never in the Germantown house.

At one point, Jones looked over at her brother and cried, "I'm sorry," and began crying.

As Tiffany Jones was being led from the courtroom, she called out: "I miss you, bro."

"I know," Jones replied.

Mattox and Tiffany Jones - both said they remain in a relationship - testified on the second day of the prosecution's case against Marcellus Jones.

Jones, 37, of South Philadelphia, is charged with tailing Zabel as the Drexel University teaching fellow walked home after his shift at a Starbucks store at Ninth and South Streets.

Prosecutors have acknowledged that no DNA or other physical evidence will link Jones to the shooting, and for years Zabel's slaying was considered a cold case.

Instead, Coelho and fellow prosecutor Tracie Gaydos say, Jones incriminated himself through his admissions to friends and relatives that he was the one who shot Zabel in the back of the neck.

Jones is serving a life prison term without parole for his 2012 murder conviction for shooting Taylor, 19, of South Philadelphia, who prosecutors say drove the getaway car the night Zabel was killed.

Giuliani has argued that the prosecution case is built from statements incriminating Jones, made years after the fact, from people desperate to earn favorable treatment from prosecutors and escape long prison terms.

215-854-2985@joeslobo