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Case Description
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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, st ...Read More
Last Seen: Oct 10, 1994
Links to Additional Sources (4)
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Victim Details

Jan 24, 2026

Jan 24, 2026

Mark

Patrick Nielsen

41

41

5'8 inches

185 lbs

White

Male

Nielsen was last seen in San Luis Obispo County, California on October 10, 1994. He lived in Los Osos. He has never been heard from again. Nielsen's family did not report him missing until January 19, 1995, three months after he was last seen. Few details are available in his case.

Oct 10, 1994

San Luis Obispo County

California

San Luis Obispo County

3

San Luis Obispo County Sheriff's Departmen

805-781-4550

01/25/2026