Thetsombandith was last seen in San Diego, California on August 18, 1991. He had moved from his native Laos to live with relatives in San Diego in 1989. He decided to stay there permanently. At the time of his disappearance, he was living with his uncle. Thetsombandith was walking in the 6000 block of Brooklyn Avenue at 7:30 a.m. when he was abducted by four or five men and forced into a white or gray 1991 Buick Skylark at gunpoint. He left one white shoe behind.

Percyval Leslie Dryden was later convicted of Thetsombandith's murder. Authorities believe Dryden had mistaken him for someone who had broken into his car the night before. Dryden claimed he just talked to him and then let him out of the vehicle a block away. Thetsombandith has never been heard from again.

Dryden was sentenced to 19 years to life in prison. He never revealed the location of Thetsombandith's body. Foul play is suspected in her case due to the circumstances involved.