The King County Sheriff's Office is trying to find Michael Boysen, the grandson of an elderly couple found dead in their Renton, Wash., home on Saturday.

An "extremely dangerous" ex-con was being hunted Monday in the Pacific Northwest after his elderly grandparents were found slain, officials said.

Michael "Chad" Boysen, 26, was staying with his grandparents in the Seattle suburb of Renton, Wash., shortly after being released from prison, King County Sheriff’s Department 911 supervisor Susan Chapin said.

A relative became concerned when she couldn’t reach the grandparents and they did not return phone calls. When she drove to their house, she found their bodies about 7 p.m. (10 p.m. ET) local time Saturday, Chapin said. Their names have not been released.

Police confirmed that a warrant had been issued for Boysen's arrest on suspicion of first-degree murder.

“He was staying there. The couple’s car was taken. There was no sign of forced entry into the home. He was just released from prison after serving a year for burglary,” Chapin said.

Further investigation indicated that Boysen had been searching online for places to buy guns, including gun shows, in Washington state and Nevada.

Police have called him “extremely dangerous.”

“I think the fact that he’s believed to have killed two people who were close to him and then he starts looking for guns, we should consider him armed and dangerous,” Chapin said.

Washington state’s gun laws require a waiting period for handguns purchased through a dealer.

Boysen is 5 foot 10 and 170 pounds with dark hair and hazel eyes. He is thought to be driving a red 2001 Chrysler 300. The car’s original tags, which may have been changed, were Washington plates bearing the number 046 XXU.

Police say that Boysen should not be approached and that anyone who sees him should call 911 immediately.

"I can't stress how dangerous this guy is," King County Sheriff John Urquhart said at a Monday news conference. He said Boysen had made threats against family members and law enforcement officials, but he did not elaborate.

"We have to catch him as soon as we can," Urquhart said.

Urquhart said the grandparents were not shot, but he declined to provide other details about their killings, pending autopsies.

The Associated Press contributed to this story