Defendant Joel Courtney, 43, avoided a possible death sentence by pleading guilty Monday to aggravated murder after revealing the location of Wilberger's remains.
The developments ended one of the most publicized murder investigations in Oregon history and brought long overdue relief to the family of the 19-year-old victim.
"It might be hard for you to understand, but at this time we really feel gratitude, even to Mr. Courtney," said Cammy Wilberger, the mother of the teenager.
Courtney was sentenced to life in prison without the possibility of parole after entering the plea in Marion County Circuit Court in Salem.
Benton County District Attorney John Haroldson made the surprise announcement in the case of the Brigham Young University sophomore who vanished in May 2004 from an apartment building near the Oregon State University campus in Corvallis.
"He abducted her, he raped her, he murdered her and left her body in the woods," Haroldson said.
The prosecutor once vowed to seek the death penalty in the case, but Wilberger's family said they would support a plea deal if Courtney would reveal the location of the her remains.
"Our family has kind of likened this to an iceberg experience," Cammy Wilberger said. "Although what the public sees seems raised and maybe devastating, it's nothing compared to what we see on the inside."
Police found strands of Wilberger's hair among evidence collected from Courtney's van when he was arrested in 2005 in the rape of another student in New Mexico.
He was eventually convicted in that case and extradited to Oregon to stand trial for the killing of Wilberger. But it wasn't until last weekend that Courtney admitted the crime and revealed the location of the body.
Wilberger disappeared from an apartment complex managed by her sister. Before she was kidnapped, she had been scrubbing lampposts outside the apartment building. Her flip-flop sandals were left behind.
Haroldson said Courtney has admitted approaching two other young women in Corvallis before abducting Wilberger. Those two women became alarmed and were able to avoid abduction.
Courtney approached Wilberger, trying to make it appear he was delivering an envelope, then threatened her with a knife and forced her into the van, Haroldson said.
Courtney bound her with duct tape and drove into the remote Coast Range but returned to Corvallis when he got hungry, with Wilberger in his van.
He went back to a remote spot in the mountains and raped her, and when she tried to fight him off, Courtney killed her by bludgeoning her skull, Haroldson said.
Courtney's sister told investigators Courtney began using drugs at age 11, developed an interest in Satanism by the age of 15, and once had to be hit over the head with a clock to prevent him from raping her.
He served time in jail in Oregon for a 1991 sex abuse conviction in Washington County, where he grew up.
Courtney grew up in the Portland area before moving to Alaska, Florida and New Mexico, working at times as a fisherman, mechanic and janitor.
He eventually married and settled in Rio Rancho, N.M., an Albuquerque suburb.
As part of the plea deal, Courtney will be returned to New Mexico to serve the remainder of his 18-year sentence there before being returned to Oregon to serve the life sentence.