With a duffel bag of cash and a stolen credit card, 17-year-old Xavier Johnson took friends on a shopping spree Wednesday. They drove through West Philadelphia in the car of the foster mother Johnson had allegedly stabbed to death hours before, law enforcement sources said.

They had breakfast at McDonald’s, then went shopping for sneakers at Foot Locker — a $270 pair of Jordans for him, $70 Champions for a buddy.

“I killed a lady for all this [stuff] and I took everything she had,” Johnson told his friends, the sources said.

Minutes later, the teens crashed the car with police on their tail.

Those details emerged Thursday as Johnson was charged with the fatal stabbing of his foster mother, 64-year-old Renee Gilyard, and the earlier stabbing and beating death of Jimmy Mao, 20, who previously lived with Johnson in another foster home.

Homicide Capt. Jason Smith said at a news conference that both Gilyard and Mao “were brutally tortured and then murdered by Xavier Johnson." The motive in both incidents was robbery, he said. Johnson allegedly stole a debit card from Gilyard and a PlayStation and cash from Mao.

Before her death, Gilyard, a mother of two sons, one of them a Philadelphia police officer, had grown concerned in recent days by Johnson’s behavior, the sources told The Inquirer. She had planned to ask child welfare officials to place him somewhere else, they said.

Instead, she was found dead early Wednesday in the bathtub of her East Germantown home.

Investigators believe Johnson killed Mao before stabbing Gilyard, though they aren’t certain when. Mao’s body was found Wednesday night in a duffel bag at the bottom of a ravine in West Philadelphia.

Johnson has been in police custody since Wednesday morning, when he allegedly crashed Gilyard’s SUV with three other teens after the shopping spree.

Police are continuing to investigate whether Johnson was also involved in the disappearance of 16-year-old Jacob Merritt-Richburg, an acquaintance of Mao’s who has been missing for more than a week.

Even amid a particularly deadly start to the new year in Philadelphia — 23 homicides in 15 days — the killings stood out, and they raised questions about how officials handled Johnson’s time in the child welfare system.

Heather Keefer, a spokesperson for the city’s Department of Human Services, said she could not comment on Johnson’s case.

‘I’ll be all right’

Gilyard had lived on the 300 block of Mechanic Street for decades, said neighbor Madeline Harris, and was a block captain who frequently worked on her yard.

She began serving as a foster mother 20 years ago, Harris said, and took in only teenage boys — more comfortable talking sports than worrying about girls.

“I think she could just communicate better with the boys,” Harris said. “I remember at first I said, ‘Renee, are you sure you want to be taking these young men?’ She said, ‘Mad, I’ll be OK. I’ll be all right.’ ”

Johnson had been in Gilyard’s care for just days before she expressed concern to her son Quin, sources said. She was frustrated that Johnson repeatedly missed his 11 p.m. curfew, and on Monday night she called police to report a burglary at her home.

Gilyard told a responding officer that Johnson had missed his curfew but still managed to get into the locked house. Gilyard said Johnson could stay the night, sources said, but she planned to contact a foster care agency to have him placed somewhere else.

Investigators believe Johnson killed Gilyard sometime early the next morning. During the day Tuesday, Johnson hung out with friends in an abandoned West Philadelphia house, flush with cash and telling them he was looking for weed.

Later he asked a friend to drive him back to his foster mother’s house and park at the end of the street.

Johnson went inside and stuffed some belongings into bags, sources said, knocking over a picture frame on his way out the door.

Later that night, sources said, Johnson told his friends he’d gotten into a fight with his foster mother and did what he had to do, sources said. There was no turning back, he said.

Failed escape

Around 1 a.m. Wednesday, police again responded to Gilyard’s home, this time after relatives could not reach her. The first-floor bathroom door was locked. Gilyard was in the tub, stabbed in the neck. She had defensive wounds on her hands, sources said, and there were bloody footprints leading to her bedroom, where her purse had been emptied on the bed.

As police searched for her stolen car, Johnson and his friends spent Wednesday morning shopping, using Gilyard’s Police and Fire debit card along the way.

Soon the cops were on their tail. Johnson told his friends he wasn’t getting caught, they later told police.

The teens smashed into a flatbed truck on Sansom Street and were taken into custody. Gilyard’s debit card was in Johnson’s jacket pocket, sources said.

Hours later, police found Mao’s body near the 5800 block of Angora Terrace, the last place he was seen in December. He had stab marks on his face and neck, police said, and his body had been placed in a bag and tossed to the bottom of a hill.

On Jan. 7, Mao’s brother told police he’d received text messages demanding a ransom for Mao’s safe return. Johnson was interviewed, police said, but they did not say if that was before or after the ransom messages were sent.

Officials have not said if Gilyard had been told of Mao’s disappearance — or Johnson’s potential role in it.

Back on Mechanic Street, Gilyard’s neighbor, Harris, tried to comprehend the loss of a woman she said gave so much to children.

“Losing her and imagining a kid so full of hate and rage at 17 years old, it’s scary,” Harris said. “Not just for me, but for the world.”