Mark Thiebaut Jr., 28

Last seen: Early October 2026 — his GMC Sierra was found parked in the 700 block of Goblins Castle Road in an Estes Valley residential area; he had rented a nearby vacation home.

Investigating agency: Larimer County Sheriff's Office

Official source: view the official record

Details: 28-year-old male, of Grand Lake, CO. In early October 2026 the Larimer County Sheriff's Office received a report of an abandoned vehicle in an Estes Valley residential area; the GMC Sierra was registered to Mark Thiebaut Jr. His family had not heard from him in over a week and shared concerns about his welfare. A coordinated search of the surrounding area did not locate him; investigators found no evidence of foul play and suspended search efforts pending new leads. Anyone with information about his location or intended destination: Investigator Brent Manley, (970) 498-5336.