Russell-Torres "was calm when he told me the story and showed no emotion," an officer wrote in documents filed with the Salt Lake County jail.
The infant was flown to Primary Children's Medical Center, where doctors found injuries consistent with shaken baby syndrome but no signs of drowning, police wrote. The child died at 7:45 a.m. Sunday, according to the charging documents.
An autopsy showed signs of the fatal head and brain damage, as well as evidence that one of his ribs was likely fractured at a different time, according to the charging documents. The examiner also noted an older fracture around the left wrist, the charges state.
Russell-Torres admitted to police that he had violently shaken the baby forward and backward for a minute or two after he became frustrated with the baby's crying, according to charging documents. He said he also had shaken the baby on some previous occasion, police wrote.
"He said he realized he hurt the baby once it started showing other signs of illness, which is when he gave the baby a bath," police wrote. "It wasn't until the baby turned cold and was not breathing that the father called 911."