Video shot by WAGM-TV showed a red pickup truck and a black ATV in the middle of Route 227. The suspect remained at large on Tuesday evening.
The victims were identified as 51-year-old Roger Ellis and 25-year-old Allen Curtis, of Castle Hill. Their bodies were transported to the medical examiner's office for autopsies that are scheduled to take place on Wednesday.
The bodies were found in Ellis' red Chevrolet Silverado. Police initially thought the truck and a black ATV had collided.
Authorities are searching for the owner of the ATV, which they have determined is an unregistered 2006 Suzuki LTZ 400. The ATV was painted black over its original yellow.
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Castle Hill is a town of about 400 people just west of Presque Isle in Aroostook County.