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

Case Description

Any updates on this case? Let us know!
Summary based on 4 sources
Mark Patrick Nielsen was 41 years old when he was last seen in San Luis Obispo County, California, on October 10, 1994. A resident of Los Osos, he has not been heard from since that day. His family officially reported him as a missing person on January 19, 1995, more than three months after his disappearance. There is limited information available regarding the circumstances of his case.

At the time he went missing, Nielsen was described as a White male with brown hair and blue eyes, standing at 5'8" and weighing 185 pounds. He was reportedly wearing a jean jacket, a white t-shirt, and jeans. Nielsen also went by the nickname "Sharky".

The San Luis Obispo County Sheriff's Department is the investigating agency for Nielsen's case. His case is classified as a missing person, and his information has been entered into national databases, including the National Crime Information Center and the National Missing and Unidentified Persons System. Despite these efforts, his case remains unresolved, and he has now been missing for several decades.

Last Seen: Oct 10, 1994

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 — Modesto, California
UP13299 • Found Mar 9, 1996
View case
Sex ✓Male
Age 100%Est. 40–50 vs 41 when missing
Race 100%White
Location 75%Same state
TimingFound 17 months after last seen
Weight 100%180 lb vs 185 lb

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.