Spokane, Washington, USA | Nearly 40 years after the murder of 32-year-old Mary Ann Turner, investigators in Spokane, Washington, have identified and arrested a suspect using advanced DNA analysis and forensic genetic genealogy.
The Spokane Police Department announced that 74-year-old David Tibbett was taken into custody after investigators developed probable cause to charge him with second-degree murder. The breakthrough came through a combination of forensic DNA evidence and witness statements collected during the original investigation.
The 1986 Murder
On November 4, 1986, police officers in Spokane responded to a report of a person lying in the roadway of an alley. Upon arriving at the location, officers discovered a deceased woman nearby.
The victim was identified as 32-year-old Mary Ann Turner. Investigators determined that she had been murdered and launched an investigation to identify the person responsible.
Despite investigative efforts and witness information, the case remained unsolved for nearly four decades.
Advanced DNA Testing Reopens the Investigation
In August 2025, investigators from the Spokane Police Department submitted evidence from the case to forensic laboratory Othram for advanced DNA testing.
Scientists at Othram used Forensic-Grade Genome Sequencing® to develop a comprehensive DNA profile from the available evidence. The resulting genetic profile was then examined by the laboratory's forensic genetic genealogy team to identify potential relatives and generate new investigative leads.
These leads were subsequently provided to law enforcement for further investigation.
Suspect Identified After Nearly Four Decades
Following further investigative work, detectives developed probable cause to charge 74-year-old David Tibbett with second-degree murder.
According to the Spokane Police Department, the identification was supported by DNA evidence alongside witness statements obtained during the original investigation.
On October 21, 2026, detectives from the department's Major Crimes Unit (MCU) and Special Investigations Unit (SIU) executed a search warrant at Tibbett's residence. He was subsequently taken into custody and booked into the Spokane County Jail.
The investigation into Mary Ann Turner's death remains ongoing.
Police Appeal for Public Information
The Spokane Police Department has appealed to members of the public to share any information that could assist investigators. Authorities have particularly encouraged individuals who may have previously contacted investigators or participated in the original investigation to come forward again.
Police stated that even seemingly insignificant details could prove valuable in advancing the investigation.
Forensic Significance
The case highlights the growing importance of Forensic Investigative Genetic Genealogy (FIGG) in solving long-standing homicide investigations.
Unlike conventional forensic DNA profiling, which generally focuses on comparing DNA profiles against known individuals or criminal databases, genetic genealogy uses genetic markers, particularly single nucleotide polymorphisms (SNPs), to identify potential biological relatives and develop family-tree-based investigative leads.
By combining advanced genome sequencing, genetic genealogy and traditional police investigation, forensic scientists can help investigators generate new leads in cases where conventional methods have remained unsuccessful.
The identification of a suspect in Mary Ann Turner's 1986 murder demonstrates how developments in forensic genomics can provide fresh investigative opportunities in decades-old cold cases.