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Crime Solvers Central
298 Cases Solved. Advancing justice for missing persons, unsolved homicides, unidentified and unclaimed remains.

Case Description

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Summary based on the NamUs case record (MP12337) and 11 other sources
In the late hours of September 16, 2011, 54-year-old Mark Lawrence Bosworth, a husband and father of two from the Portland area, vanished into the night from the small town of Riddle, Oregon. He was volunteering at the popular Cycle Oregon bicycle tour, an event he had been a part of for several years. Friends last saw him around 11:00 p.m. near Riddle High School, where the event's campsite was located. He mentioned he was heading to his tent for the night but never arrived. Left behind were his bicycle, wallet, identification, and credit cards, creating an immediate sense of alarm among his friends and family. The only items he was believed to have with him were a small amount of cash, a black over-the-shoulder bag, and an iPhone with a battery that had died.

Mark's disappearance was especially concerning due to his recent health issues. A two-time survivor of non-Hodgkin's Lymphoma, he had been complaining of severe headaches just before the cycling event and had made an appointment to see his doctor for when he returned. In the days leading up to his disappearance, fellow volunteers and friends noticed a significant change in his behavior. He appeared exhausted, unusually quiet, and at times seemed confused and disoriented, occasionally seen just staring into space. His family and oncologist later expressed their grave concern that his cancer had likely returned and spread to his brain, which would explain the sudden and alarming neurological symptoms he was exhibiting. This medical condition may have caused amnesia or other cognitive impairments, leaving him vulnerable and lost in an unfamiliar area.

Immediately following his disappearance, extensive search and rescue operations were launched in and around Riddle. Dozens of volunteers, firefighters, and law enforcement combed the rural Douglas County landscape, but found no sign of Mark. The search expanded into a national effort, with volunteers calling over a thousand hospitals across the country, checking for unidentified patients who might match his description. Despite these tireless efforts and numerous tips, the case grew cold. For years, there were no significant leads until July 2017, when a woman came forward to report she had found a backpack months earlier containing Mark's debit card and iPad. A subsequent search of the area where the backpack was discovered unfortunately yielded no further clues. The investigation into what happened to Mark Bosworth remains open, though authorities have stated they do not suspect foul play and believe he has likely passed away due to his medical condition. The case is a heart-wrenching story of a man who, while battling a serious illness, seemingly wandered away and disappeared without a trace, leaving his loved ones with unanswered questions.

Last Seen: Sep 16, 2011

Possible Unidentified Matches (1)

Unidentified remains cases whose details are consistent with this person, ranked by how closely they compare. Fields that are unknown in either case are left out of the score.

75%Possible
John Doe — Cottage Grove, Oregon - unidentified case UP58583
John Doe — Cottage Grove, Oregon
UP58583 • Found Apr 26, 2019
View case
Sex ✓Male
Age 100%Est. 58–72 vs 54 when missing
Race 100%White
Location 86%60 mi away, same state
TimingFound 8 years after last seen
Height 100%5'8"–6'2" vs 6'0"
Hair 40%Brown vs Gray
Eyes 0%Brown vs Blue

These comparisons are generated automatically from public NamUs case data and are not confirmed identifications. Only DNA, dental or fingerprint comparison by investigators can confirm an identity. If you believe two cases are connected, contact the agency handling the unidentified case.

Unidentified photos are blurred because many are post-mortem. Tap a photo to reveal it.