A Chicago police officer and Abby Kowalski's oldest brother. He was fathered by a man named "Speedo" with Sheila, prior to her meeting Don Kowalski, who subsequently adopted him. He tests for and transfers into the Chicago P.D. SWAT team. Donnie is recently divorced and has taken an interest in Abby's best friend Mackie.
Appearances
Against the Wall
Guest cast, played by James Thomas
- Episode 1x01: Pilot (Jul 31, 2011)
- Episode 1x02: Raindrops Keep Fallin' on My Head (Aug 7, 2011)
- Episode 1x03: We Have a Cop in Trouble Here (Aug 14, 2011)
- Episode 1x04: The Fifth Body (Aug 21, 2011)
- Episode 1x07: Countdown to Meltdown (Sep 18, 2011)
- Episode 1x08: Memories We Fear (Sep 25, 2011)
- Episode 1x11: Wonder What God's Up To (Oct 16, 2011)
- Episode 1x12: Second Chances (Oct 23, 2011)
- Episode 1x13: We Protect Our Own (Oct 23, 2011)