Search teams resumed combing trail areas about six miles up Big Cottonwood Canyon Wednesday morning looking for a Denver man who failed to return from a Sunday hiking excursion.

Dr. Jake Gradwohl, 30, a third-year resident at University Hospital, was reported missing by colleagues Tuesday after he failed to report for work for the second day in a row.Salt Lake County sheriff's deputies located Gradwohl's car near a trail head about six miles up the canyon Tuesday afternoon.

Capt. Mike Wilkinson, who is heading the search effort, said cold temperatures, darkness and snow near the 9,500-foot level forced crews to call off the search late Tuesday night.

Four teams from Rocky Mountain Rescue Dogs, 12 deputies and an LDS Hospital Life Flight helicopter assisted in Tuesday's search.