The ground hunt for a former Montana militia leader accused of firing a gun at sheriff's deputies was scaled back Tuesday after authorities said the suspect disappeared into the woods near the Idaho border.

Missoula County Undersheriff Mike Dominick says law enforcement agents would continue to search a 50-square-mile area centered on the Lolo National Forest in the search for ex-convict David Burgert.

But Dominick said Burgert -- a practiced survivalist -- could have escaped the area where the search initially focused, possibly in a 1987 Jeep Wagoneer that Burgert owns but authorities have been unable to find.

"The area is so large we've expanded it out from a ground search to more of a road search," Dominick said. "We don't know if he's still there. We're speaking to as many people that know him as we can, trying to develop investigative leads."

Burgert, 47, is 6 feet 2 inches tall, weighs 230 pounds, and has brown eyes and brown hair. He was last seen wearing a bluish shirt and a fanny pack and is believed to be armed with a handgun and possibly a rifle. Authorities believe he had been living out of a vehicle in the area, and searchers have discovered several caches of food, weapons and gear in the search area, Dominick said.

The shift in the manhunt came as federal authorities said they had obtained arrest warrants over Burgert's alleged probation violations.

Burgert is the former leader of a Flathead County militia group known as "Project 7" that was accused of plotting to assassinate local officials and overthrow the federal government. It was named for the number "7" on the Flathead County license plates in Montana.

Burgert, who was diagnosed with paranoia, was never charged in an assassination plot. He reached a plea agreement in 2003, pleading guilty to federal weapons charges including possession of a machine gun. Four other members of Project 7 pleaded guilty in the case and received lesser sentences.

Burgert was released from prison in March 2010 after serving eight years. He was barred from possessing firearms as a condition of his release, Chief Deputy U.S. Marshal Rod Ostermilller said.

"I could best describe him as a bully," Flathead County Sheriff Chuck Curry said. "He's one of those people you're constantly dealing with -- confrontations with law enforcement, confrontations with neighbors."

Authorities have been contacting Burgert's former associates in case he attempts to return to Kalispell, his former home, Curry said Tuesday.

Curry was in charge of the Flathead SWAT team when Burgert was subject to a similar manhunt in February 2002.

In January of that year Burgert attempted to stage his death along the Kalispell River to escape a pending warrant for his arrest, Curry said.

When officers later pulled over a vehicle Burgert was driving with his girlfriend as a passenger, Burgert bailed out and ran through the woods, Curry said. That sparked an all-night chase that ended the next morning with Burgert cornered and holding a gun to his head.

After a standoff of several hours, Burgert surrendered, Curry said.

"Certainly based on what happened, Burgert is a very dangerous individual," he said.