Clark County, WA. — The Clark County Sheriff’s Office has cancelled an “Attempt to Locate” bulletin issued earlier this year for 72-year-old Matt (Mathew) W. McClure after investigators successfully located and interviewed him. McClure was sought as a potential witness in the decades-old disappearance of 16-year-old Jamie Grissim, widely believed to be an early victim of convicted serial killer Warren Leslie Forrest.
McClure was never considered a suspect. Detectives believed he may have had information about a possible sighting during the winter of 1971, but locating him required public assistance due to his connection with the region’s unhoused community. Tips from the community ultimately led investigators to him.
While the details of the interview remain confidential as part of an active investigation, the Major Crimes Unit reports that McClure’s information appears credible and aligns with known evidence—including longstanding indications that Grissim’s remains may be in the Dole Valley area.
Grissim was reported missing in December 1971. In 1972, her high school identification card was found along a roadside in Dole Valley, roughly 1.5 miles north of where the remains of two other victims—Carol Valenzuela and Martha Morrison—were discovered in 1974. Forrest was convicted in 2023 of Morrison’s murder.
Investigators emphasized that McClure is not suspected of involvement in Grissim’s disappearance or any related crime.
Based on the new information, the Clark County Cold Case Team is coordinating with Washington State Search and Rescue and Clark County Search and Rescue to conduct another targeted search of Dole Valley. The effort will employ human remains detection dogs capable of detecting remains buried for decades. The search timeline depends on weather, logistics, and resource availability.
The Seattle Division of the FBI has recently joined the investigation and is consulting on laboratory and investigative components as the long-running case moves into a renewed search phase.
About the Author
