DNA From Discarded Gum Leads to Conviction in 1980 Oregon Murder

In the end, it was a discarded piece of chewing gum, casually spit on the ground in 2021, that was the key to solving the cold-case murder of a college student that had confounded the authorities in Oregon for more than four decades.

Robert Arthur Plympton had been under police surveillance since the authorities determined that year that he was a “likely contributor” to a DNA profile developed from swabs taken from the body of Barbara Mae Tucker, who was 19 when she was murdered on the Mount Hood Community College campus in 1980.

On Friday, Mr. Plympton, 60, was found guilty of murdering Ms. Tucker after a three-week bench trial in Portland, Ore. According to The Oregonian, which reported on the investigation and Mr. Plympton’s conviction, it was the oldest cold-case homicide in Gresham, Ore., east of Portland.

On the night of Jan. 15, 1980, Ms. Tucker was expected at a class at the college, where she was studying business. She never arrived.

Students on their way to class the next morning found her “partially clad” body on a shrub-covered slope near a campus parking lot, The Oregonian reported at the time. There were signs that Ms. Tucker had been sexually assaulted, and that she had struggled with her assailant.