The 60-year-old Nicholas Notaro was sentenced Friday for killing Joseph Tarricone at a home near Puyallup in 1978.
Notaro was convicted in February of first-degree murder for shooting Tarricone twice in the head, cutting up the body with a chainsaw and burying it outside a house in Puyallup.
His sister, Renee Ray Curtiss, 55, who was also convicted of murder in the case, will be sentenced April 24.
Tarricone vanished without a trace in 1978. His whereabouts were unknown until June 2007, when a construction worker unearthed Tarricone's remains while tearing down the home where Curtiss had lived 30 years ago.
Notaro, 60, told detectives he shot Tarricone twice in the head for his sister.
Court documents state Curtiss and Tarricone had been dating, but she wanted Tarricone "gone" and asked her brother for "help with the problem." The two admitted buying a chainsaw to cut the body into pieces.
In a strange twist, Notaro had killed his own wife just a week before in Alaska. Notaro was convicted of manslaughter after her body was found.
Tarricone disappeared shortly after returning from visiting his daughter in Hawaii.
"That was the last time I saw my father," said his daughter, Gypsy Gonzales-Tarricone.
Gonzales-Tarricone said 30 years is 30 years too long to wait for closure, and she had no sympathy for the two convicted in her father's murder.
"What they did to him, they're just monsters," she said. "She (Curtiss) stole a lot from us. And I hope she pays dearly for it. I hope she goes to prison for the rest of her life."