Erthal was last seen in Oroville, California on October 11, 2006. He has never been heard from again. At the time of his disappearance, he living part-time with friends, and part-time with a roommate in a trailer park on Olive Highway not far from the Gold Country Casino. Erthal and his roommate got into a physical fight the day he disappearance. He walked away from the fight and never returned. He left his wallet and identification behind at the trailer park. About two weeks after Erthal disappeared, his roommate died of an overdose. Erthal's family reported him missing on November 8.

Erthal's mother believes her son is probably deceased and that his body is somewhere in the local area. Two days before his disappearance, he called a distant relative and said he was afraid of a group of people he knew. No suspects have been named in his disappearance. Since Erthal went missing, there have been hits with his name and date of birth on the national firearms clearance system, indicating that he or someone using his identity has been trying to buy guns.

Erthal served four years with the Marine Corps. He was unemployed at the time of his disappearance and did not have any money, and he was apparently involved with drugs. He did not have a vehicle and usually walked or used buses to get to where he wanted to go. Erthal lead a transient lifestyle in 2006 and frequented the Orovile Rescue Mission and the Chico Mission. He kept in regular contact with his family, but they haven't heard from him when he went missing. He left behind all his personal belongings, except perhaps his Marine Corps duffel bag. His case remains unsolved and foul play is suspected.