PROVO — A Provo man has been arrested for causing the death of his girlfriend's 4-month-old daughter, according to police.

Cameron Chad Willingham, 23, was booked into the Utah County Jail Wednesday for investigation of child abuse homicide.

About 7:30 p.m. Monday, emergency crews were called on a report of a baby not breathing. "When patrol officers arrived, they found an unresponsive infant with serious injuries," according to a statement from Provo police.

Nevaeh King was taken by medical helicopter to Primary Children's Hospital. She died Wednesday morning of "serious head and neck injuries, as well as abdominal hemorrhaging," police said.

She had been on life support for approximately 36 hours, according to a police affidavit filed in 4th District Court.

Doctors found swelling on the baby's brain, a fractured rib, "and multiple hemorrhages in the abdominal region and rib cage," the affidavit states. Medical crews also noted "evidence of severe dehydration and malnutrition would imply child abuse."

Willingham is the boyfriend of Nevaeh's mother. He told police he was watching the child for about four hours leading up to the incident.

"Willingham admitted to 'tossing' the infant on the bed. (He) identified that earlier he had given the baby a bottle in effort to stop the baby from 'freaking out.' This bottle was given to police and contained dried up formula and mold as if old and not applied as stated by Cameron," the affidavit says.

Despite his arrest, a woman claiming to be the baby's mother called the Deseret News Thursday to defend Willingham.

"He loved that baby girl. He would never hurt her — ever," she said. "The love of my life is in jail for something he didn't do."

The woman contends police arrested Willingham because "he was the only one around to pin it on."

Provo Police Lt. Brian Taylor, however, said detectives established probable cause and denied the woman's claims.

"That's not what we do here. We investigate according to well understood, Fourth Amendment standards," he said. "We don't just arrest the first person. We investigate according to legal standards."

A woman who used to live with the mother when she was pregnant described Nevaeh as a sweet baby.

"The baby was the most pure soul you would ever meet. She would smile at, really, anyone, once she knew how. She was calm and quiet,” said Trisha Creviston.

Court records show Willingham was convicted of misdemeanor drug possession twice in December in different jurisdictions. In December of 2016, Willingham was charged with misdemeanor assault in a domestic violence incident.

He was convicted of misdemeanor assault on a pregnant woman in September of 2016, and misdemeanor drug possession and failing to stop at an officer's commands in April of 2016, according to court records. Willingham pleaded no contest to unlawful sexual activity with a minor in 2014.

Contributing: Caitlin Burchill