Little is known about Sophia Bush's "Chicago P.D." exit last season, save for the fact that she left on her own volition, but she is slowly starting to talk. The actress, who played Detective Erin Lindsay, on the show for four seasons, recently revealed more details about her decision to leave.

While being on the lead role was pretty much her dream, Bush told Refinery29's Christene Barberich on the UnStyled podcast that she knew by the end of the second season that she could not keep doing that job. However, it was not until a year later that she sat down with her bosses to talk and give them an ultimatum.

"A year later, when I sat my bosses down -- it was in the summer between seasons 3 and 4 -- and I said, 'Here's where we are. Here's everything you're aware of. Here's how I'm coming to you today,'" she revealed. "'If something really drastic doesn't change, I'm leaving at the end of the year'..."

Bush made it clear that she gave the show 23 episodes' worth of notice to avoid being labeled "hysterical," "emotional," or "irrational." She believes that was enough time for the team to meet her requests and figured they would know ahead of time that she is parting ways if they failed, which, unfortunately, was what happened.

Bush's "Chicago P.D." exit was announced May this year. She was written off when her character was forced to accept a job at the FBI in New York in order to protect her troubled mother, Bunny (Markie Post), who had been involved in a murder investigation.

Last month, reports indicated her decision to leave had partly something to do with the off-screen conduct of fellow star Jason Beghe, aka Sergeant Hank Voight. Sources claimed he has been using "highly aggressive and sexually suggestive language" toward the cast and crew, leading to the exits of previous female cast members and Bush.

The actress did not specify whether that was the case or if it was creative-related, but it was reportedly becoming more and more unbearable. She compared it to being trapped in a burning building: "I was just so unhappy and it was my dream job and I was miserable and I had to go."

Apparently, Bush does not want to fully talk about her departure yet. However, she promises fans to go on details once she is ready.