The grandson of beloved South Philadelphia neighborhood grocer Marie Buck testified Wednesday that his stealing a gold chain from his heroin dealer led to the Christmas Eve slaying of his 81-year-old grandmother.

Robert Buck, 23, told a Philadelphia judge that he was supposed to be working in his grandmother's store on Dec. 24 but overslept.

His grandmother took his shift and shortly before 10 a.m. became the target of a gunman who stood in the door of Marie's Grocery and shot her 11 times with a semiautomatic pistol.

Buck's allegations and a chain of circumstantial evidence led police to Maurice Green, 31, the Overbrook drug dealer who Buck says fed his heroin habit.

After a preliminary hearing that ran most of the day, Municipal Court Judge Patrick F. Dugan ordered Green held for trial on murder and reckless-endangerment and four gun counts.

The hearing was marked twice by problems in the gallery, once by a spectator who took out a cellphone and, after the hearing ended, when security officers had to separate the families of the victim and the accused after they began screaming and shouting obscenities at each other.

Buck, who is cooperating with prosecutors, testified that he first began buying heroin from Green in the summer of 2015 and began sharing "free" heroin he said his girlfriend, Angela White, got from Green because she was also the dealer's girlfriend.

Last June, Buck continued, White called and said she was alone in Green's house and was considering stealing his gold chain necklace.

"I said that if she's going to take it, it's OK with me," Buck said. "Why not? You just do anything to get high."

Buck testified that he took the heavy 18-karat-gold chain necklace to a South Street jeweler and pawned it for $2,000. He said he told White he got $500 for the chain.

"Why lie?" asked Assistant District Attorney Jude Conroy, who is prosecuting the case with Joanne Pescatore.

"That's what drug addicts do," shrugged Buck. "We got high and got a hotel room in New Jersey."

In the next few months, Buck acknowledged, White was assaulted and the word on the street was that Green was looking for him. But when White resumed her relationship with Green, Buck said he assumed Green had forgotten about the theft.

The morning of Dec. 24, prosecutors alleged, Buck's grandmother paid the price.

Marie Buck opened the store at Sixth and Titan Streets with her husband, Michael, 44 years ago. The Bucks lived a few doors from the neighborhood institution.

Defense attorney Robert M. Gamburg challenged the credibility of Robert Buck and another alleged Green customer, James Burke, 29, who testified about meeting Green to buy drugs in South Philadelphia about the same time that Marie Buck was shot to death.

Gamburg got Burke to admit that he could not identify Green as the man seen in a surveillance video parking a silver Chevrolet Impala near the Buck grocery at the time of the shooting.

Burke said he could only say that he met Green that morning and that Green drove a Nissan and an Impala – both silver sedans with tinted windows.

A witness in the store also could not identify the shooter.

Prosecutors say the Impala in the video has the same hood damage and missing front emblem as the car seized, with Green's identification inside, when he was arrested Dec. 28. They said cellphone records of Green's two phones also place them in the neighborhood at the time of the shooting.