The "August: Osage County" star who's been missing since last week may have been found dead ... according to family members.
Misty Upham's family tells TMZ ... one of their search teams found a body in a ravine about an hour ago. They have not been able to reach the body yet because of the steep terrain ... but searchers believe it looks like Misty.
We're told the search team included family, friends and other members of the Native American community around Auburn, WA. They contacted police ... who are now sending officers to help retrieve the body.
As we reported ... Misty's Dad feared she had committed suicide when she went missing after going to visit friends. He says she'd recently changed the meds she was taking to control erratic behavior.