McColl was last seen departing from his family's residence near The Alameda in Berkeley, California at approximately 11:00 a.m. on August 28, 1995. He told his brother that he planned to walk to the bus stop and take a bus to Cody's Bookstore near Salon Avenue and Telegraph Avenue. McColl never returned home and has not been heard from again. His wallet was discovered after his disappearance, but his identification cards were missing. He left $100 in cash behind in his room. He had just passed his driver's test, but hadn't gotten his license yet; it arrived in the mail a few weeks after he disappeared.

The driver of the AC Transit bus 43, near the corner of Redwood Road and 35th Street in Berkeley, claims McColl asked him directions to Montclair, California on the day of his disappearance. He appeared to have a prearranged meeting with an unidentified teenaged boy whom the bus driver also saw. The boy was 16 to 18 years old with blond hair, well-dressed, accented speech. The boy has never been identified and the bus driver's sighting about McColl has not been confirmed. A cab driver claims he drove a young man fitting McColl's description, and a teenaged girl with red-streaked hair, to the airport to catch a Southwest Airlines flight shortly after McColl disappeared. This sighting has not been confirmed either and inquiries at the airline have not turned up any relevant information.

It is unclear whether McColl left of his accord. He may have traveled to Oregon, Florida, Louisiana or Washington after his disappearance. McColl is a guitar player and served as a rower on his high school's crew team. He enjoyed hiking along the trails of Tilden Park and riding his mountain bike in the Berkeley Hills, and he also liked music and poetry. An extensive search of the area produced no clues as to McColl's whereabouts. He was an honors student in 1995, and disappeared only a week before the start of his junior year at Berkeley High School.

McColl's family members said that he did not place any unusual phone calls and wasn't behaving strangely prior to his disappearance; on the contrary, he appeared to be happy with his life. It is uncharacteristic of him to leave without warning, and he was not carrying any additional clothing or money when he vanished. There were several religious groups recruiting on the campus of the University of California at Berkeley, where McColl's father was then a professor, at the time of his disappearance. McColl is described as a deep-thinking, spiritual person, and his parents looked into the possibility that he had joined one of the groups, but they could find no evidence to support this theory. His family no longer lives in the Berkeley area. McColl's parents now live in Poulsbo, Washington, where they run a foster care facility for troubled teens; his sister lives in Seattle, Washington; and his brother lives in San Diego, California. McColl's case remains unsolved.