Murder suspect Michael “Chadd”  Boysen spent Saturday night in a Tukwila hotel room, hours after his grandparents were killed in their Fairwood home, according to the King County Sheriff’s Office.

King County Sheriff’s detectives learned Monday that Boysen used his real name to check into the Extended Stay America in the 15600 block of West Valley Highway Saturday afternoon and had spent one night before leaving, according to Sgt. Cindi West, a spokeswoman for the Sheriff’s Office.

The Sheriff’s Office offered the new revelations Wednesday evening.

The bodies of his grandparents, Robert and Norma Taylor, were found on Saturday by their daughter hours after they were killed.

Detectives are declining to share information about the homicide crime scene but said the cause of death will likely be released by the King County Medical Examiner’s Office on Thursday afternoon.

Boysen will stay in Oregon until he is extradited to Washington. 

Boysen was taken into custody Tuesday night after an hours-long standoff at a hotel in Lincoln City, Ore.  An employee of the West Shore Hotel in the coastal city had alerted police that Boysen had checked into that hotel late Monday night.

Boysen is currently being treated at the Legacy Emanuel Hospital in Portland for what appears to be self-inflicted cuts. He’s in serious condition.

King County Sheriff’s detectives have been in Oregon since Tuesday, working on the investigation, according to West.

At the scene of the standoff, detectives learned that Oregon State Police had located the Taylors’  missing car in a Wal-Mart parking lot in Salem, Ore., on Tuesday.  Boysen had dumped his grandparents’  Chrysler sedan in the Wal-Mart parking lot and paid cash for a used Ford Taurus at a nearby used-car lot.