About 20 police officers and K-9 dogs continue to comb a 185 acre park in Iowa City for a missing University of Iowa professor. The search for 66 year old Arthur Miller started Wednesday when his car was found inside the entrance to Hickory Hill Park.

Sergeant Mike Brotherton says Miller may have a high-powered rifle with him, but he says not believe Miller is a threat to anyone but himself. "At this point, we’re probably looking at it more as a recovery mission," Brotherton said. "I don’t believe that Mr. Miller would be out there surviving in the park for a couple of days."

Inside Miller’s car, officers found his wallet, cell phone and ammunition. He left a note for his wife on Tuesday. Brotherton described the note as "apologetic, rather than suicidal." Miller was recently charged with four counts of accepting bribes.

The political science teacher is accused of offering better grades to female students in exchange for sexual favors. Officials at the University of Iowa are not releasing specific details, but say they have bolstered security on campus as a precaution.