Viewers of “Chicago Fire” bid farewell to Matthew Casey as star Jesse Spencer exited the primetime drama he’s been part of since the first episode back in 2012.

On the Wednesday, Oct. 20 episode, it was revealed that Casey was moving to Oregon, concluding Spencer’s 10-season run with the show.

“It wraps up 10 years for me,” Spencer said of his exit, as reported by Deadline.

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“I think it was pretty organic that he’s leaving and he’s going for three years but is he? We don’t know,” Spencer explained.

“It’s been a long time coming when you know how these compadres have gone through life and death together. It’s hard to say goodbye, you know, see you soon, kind of thing. It was bittersweet but I really enjoyed it and we got some laughs out of it,” he added.

This marks the first time in 18 years that Spencer will not be appearing in a one-hour TV drama; prior to “Chicago Fire”, Spencer spent eight seasons starring opposite Hugh Laurie in “House”.

Spencer also shared a video online featuring moments behind-the-scenes on the show with the cast and crew.

As ET reports, Spencer spoke to the press about the “difficult decision” he made to say goodbye to “Chicago Fire”.

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“We were coming up to the 200th episode. I called [showrunner] Derek [Haas] on making a personal decision and broke him the news that I thought it was time to leave the show. And he agreed that we should at least get Casey to 200 episodes,” Spencer said.

“It was a difficult decision because I’ve loved the show from the start. But there’s other things that I would like to do in the future,” he added.

“There’s some family that I need to take care of. And 18 years is a long time, that’s a long stretch,” Spencer admitted. “I was marking off these milestones and looking to the future… Derek didn’t want me to leave, but we both agreed that if it was time for me, then it was time. It was a difficult decision, and I hate to leave the show because I do love this show. But when the time comes, the time comes.”