Authorities are searching in Jackson County for Derek W. Pettigrew, a 22-year-old Fort Collins man who is believed to be armed and experiencing a mental health crisis, according to a statement released by the Jackson County Sheriff’s Office on Saturday.

Pettigrew was last seen leaving his Fort Collins residence around 9 p.m. on Tuesday, July 15. Early the next morning, on July 16, the Jackson County Sheriff’s Office was contacted by Fort Collins Police after Pettigrew’s cellphone was detected by a tower in the area.

Later that day, Pettigrew’s blue 2015 Subaru station wagon, Colorado license plate JOS-519, was found unoccupied on State Highway 127 about 3.5 miles south of the Wyoming border, with his phone inside the vehicle.

Authorities responded with an extensive search effort involving Classic Air Medical helicopters, ground teams from local and state law enforcement, and search dogs. Drones provided by the Wyoming Division of Criminal Investigation and the Albany County Sheriff’s Office were also used to scan the area, but no trace of Pettigrew has been found beyond his vehicle.

Pettigrew is described as a thin white male, 6 feet tall, 155 pounds, with blue eyes and brown hair. He was last seen wearing a black “TLD” T-shirt, plaid shorts, black slides and a gray ball cap. He is considered an experienced outdoorsman.

No foul play is currently suspected in Pettigrew’s disappearance. 

“Pettigrew’s family has been extremely cooperative with law enforcement throughout the investigation,” wrote the Jackson County Sheriff’s Office in the statement. “Our thoughts remain with them during this difficult time.”

Authorities urge anyone who sees Pettigrew not to approach and to call 911 immediately. Tips can also be shared with the Jackson County Sheriff’s Office at (970) 723-4242.