Sophia Bush is breaking her silence about her exit from Chicago P.D.

The actress starred on the NBC cop drama for four seasons but left in May after the show's season four finale, in which her character was offered a job with the FBI in New York City. When asked about her departure in August, executive producer Dick Wolf said Bush "wanted to leave" without further elaborating.

While the actress and activist has been active on social media in the months since, Bush had not discussed why she decided to leave the show. On Friday, however, while responding to comments on her Instagram page about the recent development deal she signed, Bush did offer a brief explanation.

“Took me a long time and a lot of hard work to get out of that show,” the actress said in a reply to a commenter discussing her Chicago P.D. departure. “I left because I wanted to. End of story.”

The season five premiere of Chicago P.D., written by new showrunner Rick Eid, dealt with the absence of Bush's character, Det. Erin Lindsay, head-on. The episode opened with a montage of memorable moments from her run on the show and also showed her ex-boyfriend and ex-partner Det. Halstead (Jesse Lee Soffer) looking at an old photo of the two of them at a now-empty apartment. The episode even showed the normally strong and silent Sgt. Hank Voight (Jason Beghe) taking with a woman about missing Lindsay, who had been somewhat of a surrogate daughter to him after he and his wife took her in when she was 15.

Onscreen, Chicago P.D. filled the void left by Bush by bringing back former series regular Jon Seda after the cancelation of Chicago Justice and by adding Tracy Spiridakos to the series-regular cast after a two-episode arc at the end of season four.

Chicago P.D. executive producer and Wolf Films president Peter Jankowski weighed in on Bush's exit in September, saying, "She was a big part of our show. ... It also gives us something to play and reflect upon and have our characters react to, so it does help creatively on a certain level."

However, it sounds like Bush won't be away from the small screen for long. The One Tree Hill alum signed a talent and development deal with 20th Century Fox Television earlier this week. As part of the pact, Bush will headline a pilot produced by the studio.