Sophia Bush leaving 'Chicago P.D.' after four seasons

Chicago P.D. is saying goodbye to one of its stars.

Sophia Bush is departing the NBC cop drama after four seasons.

The departure comes after a surprising seasonfinale in which Bush's character, Det. Erin Lindsay, was faced with moving to New York for an undercover assignment with the FBI's counter-terrorism unit in order to protect her troubled mother Bunny (Markie Post) who had become embroiled in a murder investigation.

The potential job change also came just as Lindsay's on-and-off boyfriend, Det. Jay Halstead (Jesse Lee Soffer), was thinking about proposing.

Offscreen, this is the latest change for Chicago P.D., which also recently saw the departure of series regular Jon Seda, who moved to Chicago Justice, as well as the exit for co-creator and showrunner Matt Olmstead, who left for a lucrative overall deal with ABC Studios.

See photos of Sophia Bush on the show:

In addition to Olmstead, exec producers Michael Brandt and Mark Tinker also left at the end of season four. Rick Eid, who most recently served as showrunner of Law and Order: SVU, will take over as showrunner for Chicago P.D's upcoming fifth season, where it will hit its 100th episode.

(It also remains to be seen if Seda will return to Chicago P.D. following Chicago Justice's cancellation earlier this week.)

Bush was one of several actors brought onto Chicago P.D. after the backdoor pilot was shown as a season one episode of Chicago Fire. Bush, as well as Soffer and Patrick John Flueger, were brought onto the Dick Wolf procedural after starring together in NBC's Hatfields & McCoys pilot, which was not picked up to series.

Like Fire, which has written out at least five series regulars in as many seasons, P.D. has also not shied away from mixing up the core ensemble. Archie Kao was killed off the show at the end of season one and Brian Geraghty departed at the end of season three.

This past season saw Chicago P.D. welcome several new recurring faces for multi-episode arcs, including Quantico grad Li Jun Li, Revenge alum Nick Wechsler, NYPD Blue alum Esai Morales, and most recently, former Revolution star Tracy Spiridakos, who was introduced in the final episodes of the season as a new member of the Intelligence Unit, temporarily taking over for Marina Squerciati's Burgess. (In real life, Squerciati was on maternity leave and is expected to return for season five.)

"We didn't start off at the beginning of this season with a big whiteboard like, who can we move out? Who can we move in? But we certainly wanted to be this season, as you do every season, ready for anything," Olmstead told THR in January. "[We thought], 'Let's be light on our feet. If there is any change, whether long-term or short-term, let's embrace it and use it as an opportunity for storytelling and conflict.'"

In addition to Chicago P.D., Bush appeared multiple times on the other Chicago shows as well as Law and Order: SVU. Her starring role on P.D. followed a nine-season run on One Tree Hill. Her other credits include Nip/Tuckand John Tucker Must Die. She next appears in the Bruce Willis film Acts of Violence.

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