Antonio Dawson's days at Chicago P.D. are numbered.

It was reported last week that actor Jon Seda, who portrays Antonio, would be leaving Chicago P.D. and bringing the character with him to the newest #OneChicago spin-off, Chicago Justice, which is scheduled to launch midseason. Dawson will be an investigator in the DA's office on Justice.

It was creator Dick Wolf's idea to transition the character to Justice - and it's nothing new for Seda, as Antonio was brought over to P.D. after originating on Chicago Fire.

"[Dick] came to me and talked to me about it. ... It was kind of from left field for me, but it really made sense when you think about it. Antonio is that link between all the shows, really," Seda tells TVGuide.com. "This is unprecedented. It's never done before in TV, where a character was spun off from one show to help create [another] one, and they're now being spun off again. So, it's uncharted waters, but it's history. ... It really is an incredible opportunity, and I'm so thankful that Dick Wolf and NBC came to me about this."

Chicago P.D.'s Jon Seda is heading to Chicago Justice

Seda confirms that Episode 8 of Chicago P.D.'s currently-airing fourth season will be Antonio's last on the show before he moves to Justice permanently. (A premiere date for Chicago Justice has not yet been set.)

So, what prompts him to leave? Seda's staying tight-lipped for now, but assures that Antonio's exit will make sense with the narrative of the show. "Within those eight episodes, there will definitely be circumstances that come up that will lead to the eventual move-over," he says. "His family and his status as a single parent definitely factors in. ... He has a real tough time dealing with his ex-wife and not being able to see his kids as much."

Seda's been spending plenty of time over on the Chicago Fire set this season, thanks to a budding relationship between Antonio and Fire's Sylvie Brett (Kara Killmer), the seeds of which will be planted in Fire's Season 5 premiere on Oct. 11. And family drama of a different kind will come into play when "some pretty dramatic stuff" happens that has a significant impact on Antonio and his sister Gabby (Chicago Fire's Monica Raymund).

Another possibility: That Antonio's departure will somehow stem from the investigation into Hank Voight's (Jason Beghe) actions at the end of Season 3, in which Voight (presumably) killed and buried the man who murdered his son.

"Without giving anything away, Antonio ... still tries to, as much as he can, do everything by the book and not sacrifice his convictions," Seda says. "So, there are certain things that are going to come up that could involve that [investigation]."

Whatever the reason for Antonio's departure, there's a good chance we'll still see him mingling with his former P.D. colleagues, given the Chicago shows' penchant for crossovers. "It's such a unique situation and it's incredible to see. Without the fans, we don't have any of these shows," Seda says. "It's a joy to be a part of it and to see it grow."

Chicago P.D. airs Wednesdays at 10/9c on NBC.