Authorities say a man who killed his grandparents in their Seattle-area home may be in a hotel on the central Oregon coast.

The King County Sheriff's Department said on its Twitter feed that police in Lincoln City, Ore., had surrounded a hotel where 26-year-old Michael "Chadd" Boysen was believed to be. Police say Boysen killed his grandparents in their Renton home after his release Friday from prison.

Authorities haven't said how they died.

King County Sheriff John Urquhart said Monday that Boysen has threatened members of his family and law enforcement. Investigators say he searched the Internet for gun shows.

Boysen is white, 5-foot-7, about 170 pounds. Police said he might be driving his grandparents' car, a red 2001 Chrysler 300 with Washington license 046XXU.