Steve Cooper is a homicide detective for the Chicago Police Department and Mackenzie Lyons' partner. They went through the police academy together and later earned their detective's badges in the same graduating class.

An Illinois-native, "Coop" is a crew-cut brunette with handsome features who's single, but dating...heavily. So it came as no surprise when he asked to partner with a female detective. His superiors only agreed because of Lyons' reputation as a hard-nose, by-the-book cop.