CLAYTON, Mo. (AP) – An autopsy has determined that a St. Louis County boy found dead in the Meramec River drowned.

The body of 12-year-old Christopher Marks of Affton was recovered Tuesday afternoon about six miles downstream from where a search began. He had been missing since Sunday while on an outing with relatives in a conservation area.

St. Louis County Police spokesman Rick Eckhard announced the autopsy results on Thursday. Police have said Christopher and other youths had been drinking with an adult present. Police say they are investigating whether Christopher’s stepfather provided alcohol, or if alcohol contributed to his disappearance and death. Toxicology results are still pending.

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