A St. Paul man told police he was frustrated with his infant son's crying when he threw the 4-week-old on the ground, causing fatal traumatic head injuries, charges say.

Orancy Chea, 23, was charged with second-degree murder Monday in Ramsey County District Court in the baby's death. Chea later described the injuries as an accident and denied wanting to hurt his only child.

He remains jailed in lieu of $1 million bail.

According to the criminal complaint:

Paramedics were called to an apartment building on the 1800 block of Stillwater Avenue around 11 p.m. Thursday on a report of an unconscious infant who had a fever of 103 degrees. Responders took the baby to Children's Hospital, where he died within an hour. The doctor told authorities that while the child showed no obvious signs of external injury, there appeared to be an old fractured rib.

An autopsy by the Ramsey County Medical Examiner revealed a litany of internal injuries, including a lacerated liver, bruised lung and broken ribs — new and healing — a skull fracture, and brain and abdominal bleeding. The cause of death was determined to be abusive head trauma associated with blunt-force trauma to the baby's chest and abdomen.

On Friday, St. Paul police searched the apartment and detained the boy's parents. A neighbor told authorities they heard a baby crying for 10 to 15 minutes Wednesday evening and cycles of pounding "as if someone were striking a wall," charges say.

During a police interview, Chea explained that the baby had been running a high fever and seemed bothered in recent days. He and the child's mother called the hospital earlier in the week and were advised to bring the baby in for medical treatment, but they decided to wait — even after Chea said the infant appeared to have a seizure Wednesday night.

The next morning, Chea put the baby in his crib while his mother slept. When he returned to check on him, the child was no longer breathing. At the hospital, doctors told his parents that the boy wasn't improving and had fluid in his stomach.

When told that the child had injuries new and old, Chea allegedly responded "Oh, Jesus." Police explained that sometimes people get frustrated with infants and "respond badly," pressing him on whether that's what happened. He initially denied any involvement and also said the child's mother had not mistreated the baby.

Eventually, Chea admitted to losing his temper and causing the injuries, which he described as an accident. He told police that on Wednesday night, as the child's mother slept, he threw the baby down on his back because he was crying.

The infant struck his head on the carpeted floor.

Chea denied wanting to hurt the child and broke down during the interview, saying "Oh, my God."