In Montana, searchers are using a Blackhawk helicopter and all-terrain vehicles to hunt for a high-profile prison escapee.
Kelly Frank was once accused of plotting to abduct comedian David Letterman's son.
Frank, 45, escaped Friday from a prison in Montana with another inmate, 22-year-old William Willcut. Officials warn they may be armed. Frank was accused of plotting to kidnap Letterman's son in 2005.
"We have reason to believe that they are still together, and we've obviously stumbled on tracks to work with," Montana State Prison warden Mike Mahoney said.
The fugitives, working on a prison ranch as part of a rehabilitation program, stole a truck and were spotted fleeing into the mountains.
"This big white sprayer truck came flying up this road at 50 miles an hour," said Cathy Jetty, a U.S. forest service volunteer who saw the pair on the run.
Will Letterman Laugh It Off?
Frank, who worked as a handyman on Letterman's Rocky Mountain ranch in Montana, was arrested in 2005 for allegedly plotting to kidnap Letterman's then-1-year-old son, Harry. Frank pleaded not guilty but got 10 years in jail for overcharging Letterman.
At the time, the comedian took it all in stride.
"I don't think I'll ever get tired of seeing my house on television while I'm in my house watching television," Letterman said on a March 2005 show.
Frank's fiancee, Laurie Johnson, defended his character in an exclusive 2005 interview with "Good Morning America."
"He's a very compassionate man and he would never do anything to harm someone," she said.
Local and federal authorities continue to focus their efforts in the mountains south of the prison, where the truck was found. Meanwhile, Letterman has not commented publicly on the escape.