The snowmobile of Ronald Wallace Jr., who has been missing since Sunday, was discovered Thursday by a dive team in Groundhog Reservoir, according to the Dolores County Sheriff’s Office.

“What was a search and rescue operation has moved into a recovery mission,” the Sheriff’s Office said in a news release.

On Tuesday, a multi-agency search was initiated for Wallace, a 37-year-old Groundhog-area resident and Air Force veteran.

Wallace was last heard from Sunday afternoon. He called a friend via telephone during a short break from a snowmobile ride he was enjoying in the Groundhog area. A family member reported him missing Tuesday morning.

Search and rescue teams and friends mobilized to the Groundhog area on snowmobiles. Helicopters searched the area Tuesday and Wednesday in cooperation with ground crews.

A dive team from Lewis-Arriola Fire Department was called in Wednesday and Thursday to search areas of the Groundhog Reservoir with thin or no ice and evidence of snowmobile tracks.