The hunt for an escaped Wyoming killer and his stepson has expanded to five northwestern states after an air search in north central Montana failed to locate the fugitives' vehicles.

The search area for Shannon Parazoo and his stepson, Alonzo Howard Durgin, now includes Wyoming, Montana, Idaho, Washington and Oregon.

Based on tips, authorities believe the fugitives will stay in rural areas, U.S. Deputy Marshal Rex Fullmer said Wednesday.

Parazoo and Durgin escaped from the Casper Re-Entry Center's work-release program Feb. 9.

Parazoo was convicted of second-degree murder in 1985. Durgin was convicted of aggravated assault and aggravated robbery in 1997.

Federal charges for unlawful flight to avoid prosecution have been filed against both fugitives, Fullmer said. That charge carries with it a maximum prison sentence of five years.

Parazoo, 43, and Durgin, 28, will likely face state escape charges as well.

Parazoo's wife, Rose, is believed to be with the escapees. If authorities can gather the evidence, they will charge her with aiding and abetting a fugitive, Fullmer said.

Following multiple sightings of the fugitives in north central Montana, authorities on Tuesday conducted an extensive air search of the area.

However, neither of the fugitives' vehicles - a gold Dodge Durango and a maroon Oldsmobile Cutlass - was seen.

"The fact that we can't find either of those vehicles is the reason we are going to expand that search area," Fullmer said.

He declined to say why the Marshals Service is focusing on the five northwestern states.

Shannon Parazoo's van was found one week ago in a remote area of Montana, 12 miles from the Canadian border. Authorities are still investigating whether the fugitives are in Canada, Fullmer said.

Parazoo was serving a 20- to 30-year sentence for the murder of a Gillette man. He had been in the work-release program since last year, after serving time at Wyoming State Penitentiary in Rawlins and the Casper Re-Entry Center's long-term substance abuse program, said Department of Corrections spokeswoman Melinda Brazzale.

As part of the work-release program, Parazoo held a welding job at a Casper company.

On Feb. 9, he told the center he was going to work, but didn't show up. Durgin also left the center that day on a pass to see Rose Parazoo, but failed to return.

Rose Parazoo and two of her children, ages 12 and 14, were last seen that day as well.

At 7 p.m. on the night of her disappearance, her trailer appeared deserted, said her landlord, Harold Clark. Normally, the lights and television were on at that time.

The contents of the trailer, on Taxiway Drive near Natrona County International Airport, were left behind, Clark said.

Authorities suspect that Rose Parazoo willingly left with the fugitives. Someone with her description was sighted last week in Montana.

Clark, a truck driver, said he has met both convicts and described Parazoo as a mellow guy who was covered in tattoos.

"He seemed OK," Clark said. "The one who seemed kind of squirrelly, the one I had my doubts about, was that son of his, Alonzo."

Authorities are offering a $1,000 reward for each fugitive. Anyone with information on their whereabouts should call 911.

Reach Joshua Wolfson at (307) 266-0582 or at josh.wolfson@casperstartribune.net.