SILVER CITY, N.M. (AP) — New Mexico State Police have launched an air and ground search in the Gila National Forest for a 58-year-old Boulder, Colo., man who never returned from a run Tuesday.

Police spokesman Robert McDonald said about 18 people on foot and horseback along with three aircraft were involved in the search Thursday for Micah True, an ultrarunner featured in the bestselling book “Born to Run.”

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McDonald said the operator of the hotel where True was staying discovered him missing after going to check on his dog.

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“That’s the only reason they knew he was missing — he left his dog behind,” McDonald said. “He usually takes his dog but his dog was sore” from a rigorous run the day before.

McDonald said searchers were concerned because it still gets quite cold at night in the mountains and True was last seen in shorts and a T-shirt.

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