Mahon was an elderly detective from the property unit who briefly worked with the Barksdale detail. Dubbed as a departmental "hump", he and his partner Polk had not made a single case in property crimes over their last ten years. The two were also regarded as a pair of drunks who were incapable of driving soberly. He is punched by Bodie Broadus, a young drug dealer, when the detail raid the low rise projects. Mahon takes early retirement following his injury, and is last seen encouraging Polk to do the same.