Maurice Green's resentment festered for months over the theft of his large gold chain, authorities said, with Green believing it was taken by Marie Buck's grandson and someone else who broke into his house and later pawned it.

Police said Thursday that the 31-year-old Overbrook man, who has a history of drug arrests, finally struck back, going on Christmas Eve to Marie's Grocery at Sixth and Titan Streets in South Philadelphia. He double-parked just before 9 a.m. and took his gun with him, intending to shoot the grandson, police said.

Instead, he found the 81-year-old grocer herself.

The grandson - whose name police did not release - was supposed to work in the store that day but failed to show up. Buck, who went to the store to sub for him, became Green's target.

Homicide Capt. James Clark said Green shot Buck 11 times from the doorway of her store.

"He just went and opened up the door," Clark said. "He never even fully was one step inside the store and he fired multiple times, striking her 11 times."

Police said that Green and the grandson knew each other through the drug trade, and that Green believed it was the grandson who ripped off the chain, worth between $5,000 and $10,000.

Although Green intended to target the grandson, Clark said, he made a clear choice to shoot the woman instead when he realized the grandson was not working.

"Obviously she was the intended target. . . . He shot her 11 times," Clark said. "So, we think he went in with the intention of shooting the grandson. He opened the door and saw the grandmother, and at that point he made the choice that he was going to kill the grandmother."

Surveillance video showed Green parking a vehicle and walking toward the store minutes before the shooting, and fleeing shortly afterward, Clark said. Police were led to Green by tipsters and other evidence that Clark declined to divulge.

Buck's grandson is cooperating with authorities and will not face charges, Clark said.

"Something that he was into, unfortunately and ultimately, got his grandmother killed," Clark said. "Obviously, he's very sad, and the family is very upset."

Green was taken into custody without incident Wednesday night near his home on the 5400 block of Berks Street, police said. Authorities said they were still searching for the gun that Green allegedly used to kill Buck.

Outside her store, a Third District patrol car was parked Thursday night next to the front step overflowing with flowers, candles, and stuffed animals.

Hundreds of people braved bitterly cold winds outside the Baldi Funeral Home for a viewing for Buck.

"There's disgusting people in the world. It's a shame it had to happen to her," said Alexa Disco, 25, of Voorhees, a friend of Buck's children, as she waited in line.

"I'm glad he got captured," Disco said.

District Attorney Seth Williams called the killing "horrific" and credited good police work for the arrest.

Clark used the same word, saying it was one of the more "horrific" crimes he'd encountered.

"You have an 81-year-old grandmother, defenseless, who is beloved by the community, and to be killed in this manner is horrific. It's very sad," he said. "But we're very happy to put this to a close in a very short amount of time."

Clark said Green had 15 prior arrests.

Those arrests date to 2005, mostly in connection with alleged drug dealing, and he has several open cases as well, according to court records.

In March, Green was charged with possession with intent to deliver heroin and crack at Front and Reed Streets and was released on $15,000 bail, court records show.

In May, he was charged again with dealing heroin and crack, this time on the 1800 block of South 10th Street. He posted $10,000 bail and was released, according to court records.

Both cases are awaiting trial. Green last appeared in court Dec. 19, just five days before Buck was slain.

Police Commissioner Richard Ross called the slaying "pure evil" and said he could not understand what would make someone resort to such violence.

"It's downright evil, when you think about it, because at some point you knew who you were firing at," he said. "You knew who was in that store, and so to me it's just pure evil to do something like that."

Buck ran the store alone. She opened it 44 years ago with her husband, Michael.

The couple lived several doors away, on the 1200 block of South Sixth Street.

After the slaying, longtime customers called Buck a treasured figure in the neighborhood.

Donna Fikes, 48, called her "the sweetest person you'd ever met," and said she knew her customers and their families by name, even keeping a handwritten book with running tabs for customers who couldn't pay on certain days.

Another viewing for Buck is scheduled for 9:30 to 10:30 a.m. Friday at the Baldi Funeral Home, 1331 S. Broad St. A Funeral Mass will be said at 11 a.m. at St. Mary Magdalen de Pazzi Church, 712 Montrose St.

215-854-4225

@FarFarrAway

Staff writer Aubrey Whelan contributed to this article.