Cops investigating the possible murder-suicide of NASCAR superstar Robby Gordon's father say they've recovered a butcher knife near the body of Sharon Gordon ... TMZ has learned.
Law enforcement tells us ... the knife was collected as evidence from the scene. Cops say the significance of its discovery is unclear at this moment.
The Gordon family's attorney, Steve Nichols, tells TMZ ... the family believes the knife played an important part in what led to Bob taking his own life.
Sources tell us the knife is a strong sign there may have been mutual combat between Robert "Baja Bob" and Sharon before their deaths.
Police have said Gordon strangled Sharon and then killed himself with a self-inflicted gunshot wound.
Nichols tells us there's never been a history of violence in the Gordons' long marriage.