Oregon Man Found Guilty Of 1980 Murder After DNA From Chewing Gum Links Him To The Crime

Published March 22, 2024

Robert Plympton's DNA was matched to samples found at the scene of Barbara Mae Tucker's murder more than four decades ago.

Robert Plympton Barbara Mae Tucker

Multnomah County Sheriff’s OfficeRobert Arthur Plympton, the man found guilty of murdering Barbara Mae Tucker in 1980.

An Oregon man has been found guilty in the 1980 cold case murder of a 19-year-old college student — all thanks to a piece of chewing gum.

Four decades ago, a medical examiner determined that Barbara Mae Tucker had been sexually assaulted and beaten to death. Now, her killer has finally been identified.

According to a news release from the Multnomah County District Attorney’s Office, 60-year-old Robert Arthur Plympton was found guilty of first-degree murder. He was not convicted of rape, however, as prosecutors could not prove beyond a reasonable doubt that Tucker’s sexual assault had occurred while she was still alive.

The Murder Of Barbara Mae Tucker

On the morning of Jan. 16, 1980, students at Mount Hood Community College in Gresham, Oregon, were on their way to class when they discovered 19-year-old Barbara Mae Tucker’s body lying in a wooded area near a parking lot on campus.

For decades, Tucker’s murder went unsolved.

“Someone brutally took her away from us when she was so young, and went on living their life after,” Barbara’s sister Susan Pater told Oregon Live in 2021.

Tucker was a sophomore business student at Mount Hood Community College at the time of her death. She was on her way to class on the evening of Jan. 15 when she was spotted running out into the street from a wooded area. Witnesses recalled that Tucker was waving her arms as if trying to get their attention, but no one stopped to help.

Barbara Mae Tucker

Gresham Police DepartmentBarbara Mae Tucker was 19 years old when she was murdered on her college campus on Jan. 15, 1980.

One witness reported seeing a man emerge from the wooded area and lead her back toward campus. The next morning, her body was found “partially clad” lying in some bushes. Nearby were her purse and books.

Tucker was a tall, athletic woman. She had competed in a national basketball competition and won several awards while also pursuing a variety of hobbies, including sewing, knitting, and crocheting. Family and friends described her as goofy and ambitious. She loved the arts, wrote poetry and music, and planned to one day open her own craft supply shop.

A major breakthrough in Tucker’s case came when Cece Moore, a genetic genealogist who runs a group known as DNA Detectives, tested genetic material that was collected from the crime scene and plugged it into a database called GedMatch.

The analysis showed that Robert Arthur Plympton was a “likely contributor” to the DNA profile. He was placed under police surveillance in 2021.

Robert Plympton’s Criminal History Reveals A Dark Past

As police began digging into Plympton’s past, a more sinister picture of the man came into focus. In 1985 — five years after Tucker’s murder — Plympton was convicted of second-degree kidnapping in Multnomah County, for which he served a 30-month sentence.

Between 1993 and 1997, Robert Plympton served two more six-month sentences for DUI charges and parole violations. He was also accused in 1997 of attempted sodomy and assault in an attack on a woman, although the case was ultimately dismissed as a grand jury found insufficient evidence to file a criminal complaint.

While these incidents alone didn’t point to Plympton being Tucker’s murderer, they showed that he was, at the very least, a violent and dangerous person.

Barbara Mae Tucker Murder

The OregonianA newspaper headline about Barbara Mae Tucker’s murder.

When investigators saw Robert Plympton spit a piece of chewing gum onto the ground in 2021, they collected it and sent it off for analysis. The DNA profile developed from that piece of gum matched the vaginal swabs taken from Tucker’s body during her autopsy.

Plympton, who was 16 years old at the time of the murder, pleaded not guilty. He claimed that he did not match the description of the man seen leading Tucker into the woods that night.

While Plympton’s lawyers argued that there was reasonable doubt their client had killed Tucker, Judge Amy Baggio disagreed, saying at the trial, “To be clear, this court has zero doubt whatsoever that Robert Plympton beat Barbara Tucker in her head and face until she died. He did.”

Plympton is set to be sentenced on June 21.

After reading about the murder of Barbara Mae Tucker and her killer’s arrest, learn about seven baffling cases that remain cold to this day. Or, dive into the gruesome history of the Black Dahlia murder — and why it remains unsolved.

Austin Harvey
A staff writer for All That's Interesting, Austin Harvey has also had work published with Discover Magazine, Giddy, and Lucid covering topics on mental health, sexual health, history, and sociology. He holds a Bachelor's degree from Point Park University.
Cara Johnson
A writer and editor based in Charleston, South Carolina and an assistant editor at All That's Interesting, Cara Johnson holds a B.A. in English and Creative Writing from Washington & Lee University and an M.A. in English from College of Charleston and has written for various publications in her six-year career.