The vehicle is owned by David Jones Pedersen - known as "Red" to his friends and family. He's been missing since last month, when his wife, Leslie Pedersen, was found stabbed to death in their Everett, Wash., home.
Authorities have not identified the deceased white male found in the Jeep, but they said that Red Pedersen's relatives have been notified.
An autopsy is tentatively scheduled for Monday to confirm whether the body is that of Red Pedersen and how the man died, authorities said Saturday.
Authorities have implicated Pedersen's 31-year-old son, David Joseph Pedersen, and the son's 24-year-old girlfriend, Holly Grigsby, in what an Oregon county sheriff's captain called a "vicious, vile reign of terror" that began last month. There were arrested Wednesday.
Led by a tip into remote forested mountains southeast of Salem, Ore., authorities discovered the Jeep at the bottom of a steep embankment beneath a logging road, near a campground in the Cascade Range open only in the summer. The terrain is so difficult, they struggled to get it to a position where they could discover the body.
"It took some time to come up with a plan to bring the vehicle up to a place where investigators could safely see inside," said Everett Police Sgt. Robert Goetz.
Authorities weren't yet sure whether the body was injured before the Jeep went over the embankment, Goetz said.
Red Pedersen has been missing since Sept. 28, when his wife, Leslie Pedersen, 69, was found stabbed to death in the mobile home they had moved into just weeks earlier. Her hands were tied with duct tape, a bloody pillow was wrapped around her head.
There was no sign of Red Pedersen and his black 2010 Jeep Patriot, or of his son who'd recently been released from the Oregon prison system where he'd spent half his life. Red Pedersen wanted to reconnect with his son, a relative told The Daily Herald of Everett, Wash.
Leslie Pedersen's daughter, Lori Nemitz, also spoke of the younger Pedersen to Seattle's KOMO-TV: "He's not our stepbrother; he's nothing to us."
Three days after Leslie's body was discovered, 19-year-old music-lover and devout Christian Cody Myers left for a jazz festival on the Oregon Coast. Somehow, authorities say, he crossed paths with a couple running from the law. His body was found in a forested area near Corvallis, Ore., with gunshot wounds to the head and chest. It was discovered some 70 miles from the embankment where Red Pedersen's Jeep came to rest.
On Wednesday, nine days after Leslie Pedersen was found dead, the suspects were apprehended driving Cody Myers' Plymouth. Two loaded handguns and a rifle were in the car.
The day of the arrest Yamhill County Sheriff's Capt. Ken Summers told the media, "A vicious, vile reign of terror that's affected the west coast of the United States has come to an end. The predators are off the street."
Pedersen and Grigsby have not been charged in the Oregon and Washington slayings, but they remain in custody in California on weapons and auto-theft charges. They pleaded not guilty to those charges Friday and are expected in court Tuesday for an extradition hearing.
Pedersen is a mixed marital arts competitor with a prominent white supremacy tattoo on his neck. He spent the ages of 16 to 31 in one form of incarceration or another, save for a one-year stretch in the mid-2000s. His convictions include assaulting a police officer and threatening a federal judge.
While in prison, Pedersen couldn't avoid trouble. Major disciplinary infractions included assault, extortion, disobedience, harassment and destruction of property.
Grigsby spent time in prison for a variety of charges beginning in 2006, including identity theft and unauthorized use of a vehicle. After completing probation, she was again sentenced in 2008 on identity theft charges and served two years.
Grigsby's white supremacist leanings were made clear to her fellow inmates at Oregon's women's prison. She found herself in trouble while locked up, getting written up for assault and possession of contraband.
Associated Press writer Gene Johnson in Seattle contributed.