The unidentified, 30-year-old woman had been trying to get the attention of police by driving the wrong way on one-way streets and running red lights when she spotted an officer making a traffic stop about 3:45 a.m. in Billings.
She stopped the car, "bailed out, ran by the cop and said she'd been kidnapped and he had a gun," police Lt. Mark Kirkpatrick said.
Guy Hanway Jr., 28, of Deer Lodge, Mont., "was just coming out of his drunkenness at the time" and was arrested without incident, Kirkpatrick said.
"I have never encountered someone that's been through what this young lady's been through that had the demeanor and common sense and ability to think on her feet like this," he said.
FBI spokesman Dave Joly said Hanway will face a federal kidnapping charge, along with other charges in both states. It was not immediately clear if Hanway had an attorney.
He had been in custody in Wyoming since Sept. 24, when he was arrested for investigation of aggravated assault in Riverton. The arrest came eight days after Hanway was released from prison and placed on probation in Montana.
After the arrest in Wyoming, Hanway was taken to the Pine Ridge Mental Facility after a suicide attempt, Fremont County Sheriff Jack Hornecker said. He escaped the secure site about 9 p.m. Thursday after assaulting two staffers, Hornecker said.
Hanway entered the woman's house through an unlocked door, changed into clothing belonging to her male roommate, who was not at home, and forced the woman to drive him to Montana, Kirkpatrick said.
"We're not sure if his intent was to go to Great Falls, where he may have relatives," Kirkpatrick said, adding that Hanway also mentioned going to Washington state.
"Somewhere along the line he obtained alcohol and started drinking. She was driving, he passed out," Kirkpatrick said.
Hanway has a 2003 conviction for partner or family member assault. He was sentenced to four years in prison for escaping from the Billings prerelease center in September 2006 and spent time at the Montana State Prison and Crossroads Correctional Center in Shelby. He was released on probation on Sept. 16.