Newcombe moved from Kodiak, Alaska to Seattle, Washington in 1989. He had worked as a carpenter in Alaska, building and remodeling houses, and was trying to set up a business in Seattle, but he disappeared before he could do so. On April 17, 1989, he left his Seattle home and never returned. He has never been heard from again. Newcombe's pickup truck was found parked across the street from the Alaska ferry terminal the next morning. His carpentry tools, wallet and identification were inside it. He also left behind his eyeglasses, contact lenses and an uncashed check.

There are indications that Newcombe was in Wyoming and Montana after his 1989 disappearance. Authorities believe he may have left of his own accord and established a new identity under a new name. His case remains unsolved.