A California woman staying in a Shadyside Airbnb was charged with homicide Sunday in connection with the death of a 6½-week-old Pittsburgh boy.

Nicole Virzi, 29, of San Diego, said the boy, identified as Leon Katz, fell from a bouncer seat Saturday night while she was watching him in a Shadyside apartment, a criminal complaint said. The boy’s parents had taken one of their other children to the hospital at the time Leon was fatally injured.

“Obviously, we’re at the beginning of our investigation and the charges are serious and significant,” said attorney David J. Shrager, who represents Virzi. “A thorough investigation is important in any case like this.”

Virzi is “a Ph.D. student with absolutely zero criminal history,” Shrager said. She is not studying in Pittsburgh, and her relationship with the boy is unclear.

Virzi denies any wrongdoing, her attorney said.

Pittsburgh police were dispatched to the 6000 block of Walnut Street after Virzi called 911 at 11:17 p.m. Saturday, the complaint said. She said the baby had suffered a bump to his head.

Virzi was staying in a nearby Airbnb on South Graham Street when asked to care for the baby, the complaint said.

First responders rushed Leon to UPMC Children’s Hospital of Pittsburgh, where doctors pronounced him dead at 5:47 a.m. Sunday, police said.

The Allegheny County Medical Examiner’s Office on Sunday ruled the death a homicide, the complaint said. Leon’s cause of death was blunt force trauma to the head.

Leon’s parents had taken another one of their children to the hospital Saturday night for an injury, the complaint said.

The parents left Leon, who was alert, conscious and not injured, in Virzi’s care while they were gone, the complaint said. A head CT scan showed Leon suffered a severe skull fracture to the left side of the head, along with multiple brain bleeds.

A doctor with a child advocacy center told police that both boys’ injuries appeared to be the result of child abuse, the complaint said. The injuries were not natural and not accidental.

Virzi told police she started taking care of Leon at about 6:30 p.m. Saturday, the complaint said. He was functioning normally — he had eaten and soiled two diapers, and had been burped.

Virzi told police she fell asleep “for a period of time while Leon was in the bouncer seat,” the complaint said. When she woke up, she went to the kitchen to get a bottle for Leon, and heard the baby screaming.

She said she found Leon lying on the floor and picked him up, the complaint said. She saw “a large bump to the left side of Leon’s head.”

Pittsburgh police charged Virzi on Sunday with criminal homicide, three counts of aggravated assault, and two counts of endangering the welfare of a child.

Virzi remained in Allegheny County Jail Monday morning. She was denied bail.

Her preliminary hearing is scheduled for June 28.

Justin Vellucci is a TribLive reporter covering crime and public safety in Pittsburgh and Allegheny County. A longtime freelance journalist and former reporter for the Asbury Park (N.J.) Press, he worked as a general assignment reporter at the Trib from 2006 to 2009 and returned in 2022. He can be reached at jvellucci@triblive.com.