A woman called police Friday evening after finding her father dead in the garage of his home, located in the 15000 block of NE 192 Street.
The man, who has not been identified but is thought to be in his 70s, had obvious head trauma, according to the King County Sheriff's Office.
The man was found by family members, and obviously they were pretty shocked when they got there and they found him, deputies said.
Deputies would not comment on why investigators believe the death was suspicious, but did say that there's enough things that don't add up.
Detectives from the county's Major Crimes Unit are on scene and are expected to remain there well into the night.
"We're really just at the very beginning of the investigation," a Sheriff's deputy said. "we have more questions than answers."