Chewing Gum DNA Trap Secures Decades-Old Murder Conviction

In a sophisticated undercover operation in Everett, Washington, law enforcement officials utilised a deceptive “flavour-test” ruse to apprehend Mitchell Gaff, a serial predator responsible for cold-case murders dating back to the 1980s. The breakthrough occurred in January 2024, when Detective Susan Logothetti and two colleagues posed as representatives of a chewing gum company to obtain a viable DNA sample from the suspect.

The Undercover Operation

Dressed in promotional t-shirts and carrying marketing leaflets, the detectives approached Gaff’s residence. The suspect, wearing pyjamas, welcomed them into his home and participated in what he believed was a product survey. As Gaff chewed several samples, a detective provided a small receptacle for him to discard the gum. This discarded sample provided the saliva and DNA necessary to confirm Gaff’s involvement in the 1984 rape and murder of Judy Weaver. Gaff had previously remained elusive because he rarely left his home, making traditional surveillance and “abandoned DNA” collection—such as retrieving discarded cigarette butts—nearly impossible.

Decades of Unsolved Brutality

Mitchell Gaff, now 68, has been convicted for the murders of Susan Veacy and Judy Weaver. On 16 April 2024, Gaff confessed to both crimes. His history of violence against women spans over four decades, during which he remained largely unidentified as a suspect in these specific homicides.

• Susan Veacy (1980): In July 1980, Gaff entered the apartment of 21-year-old Susan Veacy after finding her door unlocked. He bound, assaulted, raped, and strangled the mother of two.

• Judy Weaver (1984): In June 1984, Gaff attacked 42-year-old Judy Weaver in her bedroom. To conceal the crime, he strangled her with a wire and set fire to her bed linen.

• Jacqueline O’Brien (1979): Before these murders, Gaff attacked O’Brien, then a Washington State Patrol officer, in her garage. O’Brien managed to fight him off despite being struck with a firearm and wounded with a hunting knife.

Forensic Breakthroughs

The resolution of these cases was made possible by significant advancements in DNA profiling and genetic genealogy. Forensic scientist Mary Knowlton utilised modern software, specifically “STRmix,” to isolate DNA from contaminated samples found at the 1984 crime scene. In November 2023, Knowlton entered the resulting profile into the Combined DNA Index System (CODIS), which produced a match for Gaff. Gaff’s DNA had been recorded in the database following a 1984 conviction for the rape of two teenage sisters, a crime committed while he was on probation for the assault on O’Brien.

Summary of Mitchell Gaff’s Criminal Timeline

Mitchell Gaff’s confession marks the end of a forty-year search for justice. Prosecutor Craig Matheson noted that the progress in forensic science between the 1980s and the present day was the definitive factor in closing these cases. Gaff now faces a mandatory sentence of life imprisonment without the possibility of parole.