Anthony George, 20, was awaiting arraignment Wednesday on one count each of aggravated assault and endangering the welfare of children and did not have an attorney.
George was baby-sitting his live-in girlfriend's 2-year-old triplets when a neighbor called 911 at 8:14 p.m. Sunday and reported that one of the girls was not breathing.
When police arrived, George told officers the girls had fallen down the steps like dominoes while playing in plastic high-heeled shoes, with one girl landing particularly hard at the base of the 14-step staircase, police said.
That girl, Kaiyah Beck, remained in critical condition Wednesday at UPMC Children's Hospital, where a doctor told police "there are no signs of major trauma to her head externally" and "very minor abrasions about her body," homicide Det. Dale Canifaro said in a criminal complaint.
As a result, the doctor told police, "these injuries and trauma are not consistent with a fall down stairs," the complaint said.
At a news conference, Canifaro and police spokeswoman Diane Richard wouldn't say how police believe George injured the girl. Police simply believe George hurt the girl because nobody else was there who could have inflicted such injuries and because his story doesn't jibe with the doctor's findings.
But Canifaro refused to say how he believed George injured the girl.
"That's part of our investigation," Canifaro said. It's not even clear if the girls were ever on the steps, or whether that played a role in the girl's injuries.
"It's possible they were, and it's possible they were not," Canifaro said.
The other two triplets were treated for minor injuries that night - bruises and a split lip - but George is not charged with hurting them, though Canifaro said that remains under investigation.
George was first arrested about 3:30 a.m. Wednesday, on a bench warrant for missing a court appearance on domestic assault charges that stem from a fight with a previous girlfriend in March, Canifaro said. He was found while hiding at a friend's house.
Once police got additional information from the doctor, they filed the assault and endangerment charge involving the triplet.
George is charged with endangerment because he allegedly didn't "promptly provide medical care for (a) seriously injured child under his care," the complaint said.
Police said George is not the triplets' father. Their mother, Jennifer Yali, 25, went to play bingo with a friend and left George to baby sit about 6:45 p.m. Sunday.
Police said Yali called a neighbor at 8:01 p.m. and asked her to check on the triplets because George had just called Yali at bingo to say one of the triplets wasn't breathing.
The neighbor told police she had heard George yelling about 7:45 p.m., and she called 911 when she went next door and confirmed that one triplet wasn't breathing.
Yali does not have a listed phone number.