Philadelphia law enforcement officials on Thursday said they had charged one man and identified two additional suspects in last week's quadruple slaying in Southwest Philadelphia, and for the first time described it as a drug deal that turned into an armed robbery and then a slaughter.

Officials said the victims included two men who were attempting to sell a stash of drugs they found in a house they were renovating on the 5100 block of Malcolm Street. But the three men who came to purchase the drugs on Nov.18 instead shot the men — and two females with them — in the head. Police found the bodies the next day in the unfinished basement after relatives requested that they check on the well-being of the victims.

Arrested on murder and other charges Wednesday was Jahlil Porter, 32. He has seven prior arrests, most for nonviolent offenses, including drug dealing, gambling, and theft, records show.

A second suspect was taken into custody Thursday but has not been charged, while a third suspect is known to police but has not been arrested, Homicide Capt. John Ryan told reporters during a news conference also attended by Police Commissioner Richard Ross and District Attorney Larry Krasner.

Ross refused to disclose details about the type of drugs involved and their street value, but said the motive was senseless.

"Four people were violently killed, executed. It really doesn't matter how much it was, because no amount of drugs will ever justify those types of acts," Ross said. "I will tell you without going into detail that if  at some point we're able to disclose [the amount of drugs], it's going to blow your mind how insignificant it was in the grand scheme of dealing with life, and just how little these individuals had  regard for anybody else's life."

The victims were: Tiyaniah Hopkins, 20; her sister, Yaleah Hall, 17; William Maurice Taylor, 31; and Akeen Mattox, 28. Relatives said the two men recently moved into the home and considered themselves stepbrothers because they were raised together. Ryan said the two females were not involved in the botched drug deal that led to the slayings.

Ryan said Taylor,  Mattox, and one of the female victims were living in the Malcolm Street home. He said it was not clear if the male victims found the drugs they were attempting to sell in that house or in another home they were renovating.

"I'm glad that they made the arrest, because we've been praying," said Germaine Williams, maternal aunt of the slain women. "My sister has been going through a lot, we're trying to hold her up … taking it one day at a time."

She said Hopkins had been working as a packer at a warehouse and that Hall was in high school.

"I just thank God that we're getting some justice," Williams said. "I'm gong to miss my babies."

A vigil for the sisters was planned Thursday evening at Ninth Street and Lehigh Avenue. Their funerals are scheduled for Dec. 6

Reached by phone Thursday, Greg Brinkley, Taylor's uncle, was relieved by news of an arrest in the case one day after he buried his nephew.

"Needless to say, as a family, we're anxious for a resolution to these senseless killings. It's like God answered a prayer," he said. "Our family is big and close, and this didn't sit well with us. I'm glad the cops caught them. I can't account for how much this thing has hurt our family. This shouldn't have happened.

"I'm a frequent critic of the cops," added Brinkley, a retired state correctional officer. "But I need to be very clear about my appreciation to Police Commissioner Ross for the time he gave to this case. I want to thank him on behalf of my family. And I want to give major kudos to the detectives who worked on this case. What they've done helped our family big time, and it has tempered our anger."

Officials did not disclose what led them to Porter and the other suspects. Krasner chalked up the break in the case to a "combination of some very old-time gumshoe tactics and some technology." He said Porter has been charged and jailed on four counts of murder, robbery, unlawful restraint, and conspiracy, and a weapon violation.

"It doesn't matter how many people are killed; we care just as much about every single victim. Sometimes you're able to crack the case and sometimes you aren't. But thank goodness, here it was possible," Krasner said.