Two suspects in the shooting death of a 56-year-old Minnesota man were arrested Thursday night in central Utah, while allegedly driving the victim's company car, authorities said Friday.

James Fields, 26, and his 15-year-old girlfriend were pulled over by a Utah Highway Patrol trooper near Richfield, said Koochiching County Minnesota Sheriff's deputy Gary Indahl. The UHP said the pair were being held on charges of unauthorized use of a motor vehicle.A third person traveling with the two suspects was believed to be a hitchhiker, Indahl said. "It sounded like he was picked up a short time before they (the suspects) were," he said.

The deputy said Fields and the girl are suspected in the shooting death of Donald Isakson, Hermantown, a suburb of Duluth, Minn.

The victim's body was found Wednesday, about 11 miles south of International Falls. He had been shot in the back of the head with a small-caliber gun.

"His wife had reported him missing approximately 9 p.m. Monday," Indahl said. He said Fields, who listed his residence as Jackson, Miss., was on parole from a murder conviction in Texas. His girlfriend also was from Jackson, Miss.