(LINCOLN CITY, Ore.) -- A Washington state man suspected of murdering his grandparents last week is in custody after a daylong standoff Tuesday at a motel in Oregon.
Michael Boysen, 26, surrendered after state police tactical teams used breaching explosives to knock down the door of the motel room.
"The encounter went really well. The subject was already down on the floor. So there was no further resistance from him," said Keith Killian, the police chief in Lincoln City, Ore.
Killian said Boysen was treated for some self-inflicted injuries.
"They were not gun shot injuries, they were some sort of cuts," the police chief explained.
Boysen was wanted for allegedly killing his grandparents last Friday after they threw him a party to welcome him home from prison. He was released on March 8 after serving time since 2006 for three robbery convictions, according to ABC News' Seattle affiliate KOMO.
"At the grandparents' house on Friday night, there was kind of a welcome home party with other family members," King County Sheriff John Urquhart said at a news conference on Monday. "Everybody left the party at about 9 o'clock at night."
Authorities believe that Boysen killed his grandparents shortly after that and then took off in their car, a red 2001 Chrysler 300 with a Washington license plate 046-XXU.
"We are at a loss as to why he killed them," Urquhart said. "We don't know what the motive is."
The sheriff said the grandparents were not shot, but did not elaborate on how they were killed.
On Saturday, the victims' daughter, Boysen's mother, discovered her parents' bodies after going to their house when she was unable to reach them, KOMO reported.
Family members have identified the slain couple as Robert and Norma Taylor, according to KOMO. They were 82 and 80 years old, respectively.
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