The infant was airlifted to Harborview Medical Center in Seattle in critical condition, according to police spokesperson Lisa Moeller.
She says police were notified last Wednesday when the boy’s mother brought him to PeaceHealth St. Joseph Medical Center in Bellingham.
Moeller says doctors determined that the boy had head and brain injuries, as well as previous injuries, including broken bones and head trauma.
She says Melvin Johnson told police he had thrown the infant to the ground.
He was booked into Whatcom County Jail Friday.