DNA from discarded gum leads to conviction in 1980 Oregon murder

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

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

On Friday, Mr. Plympton, 60, was found guilty of Ms. Tucker’s murder after a three-week trial in Portland, Oregon. According to The Oregonian, that reported on the research And Mr. Plympton’s convictionIt was the oldest cold case murder in Gresham, Oregon, east of Portland.

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

Students heading to class the next morning found her “partially clothed” body on a brush-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 attacker.

For decades, authorities were unable to identify a suspect or make an arrest.

The first step toward a break in the case came in 2000, when vaginal swabs taken during Ms. Tucker’s autopsy were sent to the Oregon State Police Crime Lab for analysis. Laboratory technicians were then able to develop a DNA profile from the smears.

In 2021, Parabon NanoLabs, a Virginia company whose services include DNA-based forensics, identified Mr. Plympton as “a likely contributor to the unknown DNA profile developed in 2000,” according to the Multnomah County Prosecutor’s Office. said in a statement. It was not clear how the DNA connection was made; The Public Prosecution Service did not immediately respond to a request for comment on Tuesday.

Detectives from the Gresham Police Department discovered that Mr. Plympton lived in Troutdale, Ore., east of Portland and northeast of Gresham, and began surreptitiously monitoring him, prosecutors said.

When investigators saw Mr. Plympton spit a stick of gum onto the ground, they collected it and sent it to a state police crime lab, prosecutors said.

“The laboratory determined that the DNA profile developed from the chewing gum matched the DNA profile developed from Ms. Tucker’s vaginal swabs,” the district attorney’s office said.

Mr. Plympton was arrested on June 8, 2021, as he drove away from the Troutdale home he shared with his wife and son, The Oregonian reported.

He had a criminal record, including a conviction for second-degree kidnapping in Multnomah County in 1985, according to the Oregon Department of Corrections.

Mr Plympton was 16 when Ms Tucker was murdered. Witnesses reported seeing her with a man the night she was killed, and several people reported seeing her running into the street clutching her arms, perhaps in an attempt to ask someone for help, The Oregonian reported.

Kirsten Snowden, Multnomah County’s chief deputy prosecutor, said during the trial that there was no evidence that Ms. Tucker and Mr. Plympton knew each other, according to The Oregonian.

Mr. Plympton’s attorney, Stephen Houze, said during the trial that there was “undeniable, unavoidable reasonable doubt” about who killed Ms. Tucker, according to The Oregonian. He said witnesses had described the man seen with Ms Tucker – who was almost six feet tall – as being about her height or taller, but Mr Plympton was closer to six feet tall. He also said investigators never tested Ms. Tucker’s clothing for DNA evidence.

“We will appeal and we are confident that his convictions will be overturned,” Mr. Houze and his law partner Jacob Houze said in a statement on Tuesday.

Multnomah County Circuit Court Judge Amy Baggio found Mr. Plympton guilty of one count of first-degree murder and four counts of “various theories of second-degree murder,” the district attorney’s office said.

“To be clear, this court has no doubt whatsoever that Robert Plympton struck Barbara Tucker in the head and face until she died,” she said during the trial. “He did.”

Judge Baggio found Mr. Plympton not guilty of assault and said prosecutors had failed to prove beyond a reasonable doubt that he assaulted Ms. Tucker while she was alive, The Oregonian reported.

Mr Plympton is expected to be sentenced on June 21. Based on his age at the time of Mrs. Tucker’s death: he faces a life sentence with the possibility of parole after 30 years for first-degree murder.

According to The Oregonian, two members of Ms. Tucker’s family cried and hugged after the verdict was announced. Ms. Tucker’s older sister, Alice Juan, said in a statement Tuesday that her family was “thrilled that this had finally been resolved.”

“I thought it might not be that way as the years went by, but Barbie was a special little girl,” she said. Her little sister, she added, “was smart, cheerful, caring, all those things.”

Kitty Bennett research contributed.