Scott Rasmus is being held for 72 hours, while he awaits possible charges.
Rasmus and the boy's mother had been arguing and Rasmus told the mother to leave the home and he would care for their child, according to Tacoma police spokesperson Loretta Cool. A friend was also at the home and said the child would be OK, Cool said.
Monday morning, the father called the mother telling her she needed to come home to care for the infant. When she arrived, she found the child not breathing and unresponsive, Cool said. The mother called police and the infant was taken to Mary Bridge Hospital in Tacoma.
Cool says bruising was seen on the baby's face and body but the extent of the infant's injuries were not known.
Rasmus will be back in court on Wednesday..e and fire.