A judge has found a Troutdale man guilty of killing a former Mt. Hood Community College student whose body was found in a wooded area near the campus in 1980 — after a trail that drew on DNA technology and a discarded piece of chewing gum found decades later.
Rather than seek a jury trial, the defense opted for a three-week trial before Multnomah County Circuit Court Judge Amy Baggio. On Friday, she found Robert Arthur Plympton, 60, guilty of one count of first-degree murder and four counts of second-degree murder.
Barbara Tucker was 19 years old at the time she was killed. Her body was discovered by students on their way to class on Jan. 16, 1980, according to prosecutors.
A view of the Multnomah County Courthouse
Courtney Sherwood / OPB
The Multnomah County District Attorney’s Office said Plympton kidnapped and sexually assaulted Tucker before beating her to death on Jan. 15, 1980.
Vaginal swabs taken during Tucker’s 1980 autopsy were sent to the Oregon State Police crime lab in 2000. That lab created a DNA profile of a possible suspect.
In 2021, a genealogist at Parabon Nanolabs, a company that does DNA phenotyping for law enforcement agencies, “identified Robert Plympton as a likely contributor to the unknown DNA profile developed in 2000,” the district attorney’s office said in its statement. Gresham police began surveillance after they found Plympton living in Troutdale.
“When they saw Plympton spit a piece of chewing gum onto the ground, detectives collected the gum and submitted it to the OSP Crime Lab. The lab determined the DNA profile developed from the chewing gum matched the DNA profile developed from Ms. Tucker’s vaginal swabs,” the statement said.
No one from Parabon testified during the trial.
“We will appeal, and we are confident that his convictions will be overturned,” Plympton’s attorneys Stephen and Jacob Houze said in a joint statement Tuesday.
Plympton remains in custody at the Multnomah County Detention Center. He’s scheduled to be sentenced by Baggio on June 21. In Oregon, first-degree murder carries a life sentence.