According to One Chicago Center, it was decided by the creative team behind "Chicago PD" that there were already too many cast members on the show after the backdoor pilot. This led to Melissa Sagemiller, Scott Eastwood, Kelly Blatz, and Tania Raymonde being cut from the cast before the actual pilot went to air.

Sagemiller does appear as a guest in the series' first episode from 2014, "Stepping Stone," as Detective Jules Willhite. Her character, along with series regular through Season 6 Detective Antonio Dawson (Jon Seda), investigated a murder by a reported drug lord in the episode. Upon being attacked by said drug lord, Willhite was shot in the neck and later died from her injuries, effectively writing the character off the show. Jesse Lee Soffer, who played Detective Jay Halstead, was brought into the cast to replace Sagemiller. Since then, Sagemiller has appeared in a 2014 episode of "Person of Interest" and in the Melissa Joan Hart-directed Lifetime TV movie "The Santa Con."

Sagemiller posted on her Instagram a picture with "Chicago PD" star Sophia Bush after Bush announced she was leaving the show. She said in the caption, "Thank you @sophiabush. Even in the beginning eps spent in Chicago PD, I knew it was a hard place for a breastfeeding mom of 2 babies. But years on that set, I can only imagine your pain. Thank you for standing up for all of us." 

Bush said in an interview with Dax Shepard on his podcast "Armchair Expert" that she was very unhappy on the show, citing abusive behavior from a member of the crew.