(CNN) -- Washington police continued their manhunt early Tuesday for a 26-year-old man who allegedly killed his grandparents over the weekend, shortly after they held a party to celebrate his release from prison.
Michael Boysen was released from the Monroe Correctional Facility on Friday.
His grandparents picked him up, drove him around running errands, and held a gathering for family members at their home to welcome him home, said King County Sheriff John Urquhart.
The next day, the grandparents were found dead.
Authorities have not said how the victims were killed. A gun was not used, but the deaths were violent, they said.
During the course of their investigation, detectives said they learned that Boysen had talked about killing his grandparents, acquiring guns and going after authority figures.
"We need to do everything we can to get this man off the street as soon as possible," Urquhart said. "His threats against authority figures make him very dangerous and unpredictable."
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