The King County Sheriff’s Office is not saying what weapon was used to kill an elderly Fairwood couple late Friday or early Saturday, other than it wasn’t a gun.

Nor is the motive known for the slayings, according to Sgt. Cindi West, a spokeswoman for the Sheriff’s Office.

A suspect in the case, the couple’s grandson Michael (Chadd) Boysen, was welcomed home Friday at his grandparents’ home to celebrate his release from prison that day, according to West.

Boysen’s mother discovered her parents dead at their home Saturday when another family member couldn’t get in contact with them.

The Sheriff’s Office has not released the couple’s names; the Renton Reporter is waiting for the county medical examiner to officially release their identities and cause of death. The medical examiner had not released any information Monday afternoon.

Boysen is being sought by the Sheriff’s Office, with the assistance of the state Department of Corrections. He apparently left his grandparents’ home in their red Chrysler sedan. As of Monday afternoon, Boysen had not been charged with a crime.

“We need to do everything we can to get this man off the street as soon as possible,” said Sheriff John Urquhart at a press conference Monday.  “His threats against authority figures make him very dangerous and unpredictable.”

Boysen was released from the state prison in Monroe Friday after serving nine months for an attempted residential burglary in Kent last year.

Sheriff’s detectives have interviewed his friends and family members since the slayings.

“Everyone seems to think he really loved his grandparents,” West said. His grandparents picked up Boysen from Monroe and he was to stay at their home. They took him on errands Friday.

But detectives also heard from sources, whom West would not identify other than to say they are civilians and not law enforcement, that Boysen had made threats against his grandparents and others, including police.

That information was received after the couple was killed, she said. And the sources indicated he was going to buy guns to carry out his threat; Boysen had searched the Internet for gun shows sometime before or after the death of his grandparents, she said.

West said investigators are not aware of any guns that may have been at the grandparents’ home.

Investigators had no leads Monday as to where Boysen is headed, West said. Tips didn’t pan out, she said.

Police are presuming that Boysen is armed, she said.