Mark Patrick Nielsen was 41 when he was last seen in San Luis Obispo County, California, on October 10, 1994. A Los Osos resident known by the nickname Sharky, he was reported missing to family on January 19, 1995, more than three months after his last known sighting.

At disappearance he was described as a White male, brown hair, blue eyes, 5 feet 8 inches tall and about 185 pounds. He was reportedly wearing a jean jacket, a white t-shirt and jeans. The San Luis Obispo County Sheriff’s Department is the investigating agency; his information has been entered into national databases including NCIC and NamUs.

If anyone knew Mark’s habits, places he frequented in Los Osos or the county, or has information about his movements in October 1994, please share what you know with the Sheriff’s Department.