WARRENTON, Ore. -- A St. Helens man killed himself and his 10-year-old son Tuesday by running a hose from their van’s exhaust pipe to the cab area, authorities said Wednesday.

Police found the bodies of Rockland Stephens, 49, and Shane Davis, 10, on Tuesday at Fort Stevens State Park.

Warrenton police said state park employees found suspicious circumstances at a park camp site where the pair were staying. When police responded, they found the bodies of Stephens and his son in a vehicle the pair had been camping in.

Police said the condition of the bodies was consistent with carbon monoxide poisoning.

The deaths come just days after an arrest warrant was issued for Stephens. Police said he failed to return with his son from a court authorized weekend visit, leading to an arrest warrant that charged him with attempted custodial interference and contempt of court.

The boy’s mother had called Oregon State Police on Sunday and reported Stephens hadn’t returned.

Two months ago, she had obtained a restraining order citing concerns about Stephens’ conduct. But three days after the order was issued, a judge modified it and allowed weekend visitation by Stephens, according to police.

Fort Stevens State Park is located off Highway 101, 10 miles west of Astoria and near the northwestern tip of Oregon.

Columbia County district attorney Josh Marquis said an investigation into the deaths will continue, but there’s no reason to believe anyone else was involved in the killing.