King County sheriff's deputies arrested the 20-year-old father early Thursday for investigation of murder.

A neighbor to the father reported that the father rushed to his apartment Sunday evening asking for help for his son. The neighbor performed CPR on the baby and called 911. Fire department medics were called to the apartment Sunday on a report that the 3-month-old boy was not breathing. When they arrived, they decided to call police.

The baby spent four days in the hospital before dying of injuries sustained from what police are calling child abuse. They arrested the father without incident a the couple's apartment.

"It's tragic. We're talking about a young child who is too small to do anything wrong," said Rodney Chinnick with the King County Sheriff's Office. "We're talking about somebody that's defenseless and it's terribly sad."

Police aren't saying exactly what the circumstances were surrounding the baby's death. The sheriff's office says a 17-month-old boy also has been taken from the home and placed in protective custody.