Multnomah County Circuit Judge Amy Baggio on Friday found Robert Plympton, 60, guilty of first-degree murder in the death of Barbara Mae Tucker, KOIN-TV reported.

Plympton was not convicted of rape or sexual abuse because prosecutors failed to prove beyond a reasonable doubt that it happened while she was still alive, the judge said.

A medical examiner determined Tucker had been sexually assaulted and beaten to death.

In 2021, Gresham police arrested Plympton after they said DNA technology linked him to the crime.

Tucker was expected at a night class at Mt. Hood Community College on January 15, 1980. Witnesses said she had been seen running out of a bushy, wooded area on campus and that a man came out of the area and led her back to campus. A student found Tucker's body the next day near a campus parking lot.

Physical evidence from the scene was maintained and a DNA profile match eventually led investigators to Plympton.

Multnomah County Chief Deputy District Attorney Kirsten Snowden said there was no evidence that Tucker and Plympton knew each other, The Oregonian/OregonLive reported.

Plympton said he was innocent and that he didn't match the description of a man seen pulling her into the bushes.

He is scheduled to be sentenced in June.

Australian Associated Press