SAN DIEGO -- An autopsy shed no light Wednesday into the mysterious death of a 23-year-old Orange County man who vanished after leaving a Gaslamp Quarter bar and turned up dead three days later in an alley miles away.

The postmortem exam on the remains of Dane Williams of Huntington Beach revealed no clear cause of death, leaving that ruling on hold pending toxicology tests that could take weeks to complete, according the San Diego County Medical Examiner's Office.

A passing motorist found Williams' body near Landis and 52nd streets about 6:30 a.m. Tuesday, wrapped in a blanket and clad in the clothing he was wearing the night he went missing, according to police.

He appeared to have suffered no injuries that might have caused or contributed to his death, San Diego Police Department Lt. Kevin Rooney said.

Williams disappeared around 2 a.m. Saturday after leaving a bar at the Hard Rock Hotel on Fifth Avenue, near Petco Park.

He did not return to his rented room and failed to show up later in the day for an Action Sports Retailers trade show he had been working at the San Diego Convention Center.

Williams was employed as a marketing intern with Hurley International, a Costa Mesa clothing company that specializes in skate and surf wear.

According to his relatives and friends, he was reliable, did not dabble in drugs and was not prone to violence.

His family reported him missing Saturday and spent the next several days posting missing-person fliers in and around the downtown district where he disappeared.

A memorial service will be held for Williams Wednesday night in Huntington Beach.