Four people found shot to death in a basement last week were victims of a scheme-gone-awry to sell a small stash of drugs found during home renovations, police said Thursday. Three men are in custody.

Jahlil Porter, 32, has been charged with four counts of murder, robbery and other offenses, officials said. Police withheld the names of the two other men in custody Thursday afternoon until charges are filed.

Investigators believe the two male victims — 31-year-old William Taylor and 28-year-old Akeem Mattox — found a stash of drugs while they were renovating homes, Philadelphia police Capt. John Ryan said.

Ryan said he did not believe the drugs came from the home where the four were found shot, but it was unclear what home the stash was found in.

At least one of the men, who were raised together and called themselves stepbrothers, contacted one of the suspects to try to sell the stash of drugs, Ryan said. The deal turned into a robbery and then a murder, he said.

No specific attorney information for Porter was listed in court records. A phone call to the Defender Association of Philadelphia was not answered.

The victims, which also included two females — sisters Tiyaniah Hopkins, 20 and Yaleah Hall, 17 — were found shot Nov. 19 in the basement of the home after a family member called and asked for a welfare check. Neighbors later told police they had heard loud bangs the night before, which officers believe were the sounds of gunfire.

"They were all laid on the ground and executed," Ryan said.

Police Commissioner Richard Ross called the suspects violent and vicious, saying it was "incomprehensible" that someone could "do this to a human being."

"At a minimum, three people were collateral damage in a horrific incident," he said, later adding the women had no apparent knowledge of or connection to the deal.

Police would not say what drugs or how much were found. They also would not say which man they believe had set up the deal. But Ross said the stash was so small "it would blow your mind" that it led to such a crime.

Porter has nine prior arrests but could not recall the exact charges, Ryan.