<Li> Barbara Eve Harris as Commander Emma Crowley, the current commander of the 21st District, who shares a rocky past with Sgt . Platt . (season 3--present) </Li> <Li> Kevin J. O'Connor as Commander Fischer, the commander of the 21st District who succeed Ron Perry after his retirement . He was replaced by Commander Crowley because of the district's bad public image . (seasons 2--3) </Li> <Li> Robert Wisdom as Commander Ron Perry, former commander of the 21st District . He was killed in the second - season finale episode "Born into Bad News". </Li> <Li> Josh Segarra as Justin Voight, Voight's son . He was killed in the third - season finale "Start Digging". (seasons 1--3) </Li>

The cast of the tv show chicago pd