Kurtz, 59, of Gilberts, Illinois left the Timber Trails subdivision about 1 p.m. Sunday on a black Trek mountain bike.
Gilberts police said Kurtz was found alive by officers Tuesday morning and was receiving medical treatment.
The Burnidge Forest Preserve/Paul Wolff Campground in Elgin was closed Monday as forest preserve police assisted another department with the missing person case, officials said.
It reopened by Tuesday morning.
Chopper 7 was over the area Monday afternoon, and there was a large emergency response.
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