Robert Knepper is really good at being bad.

That makes him a perfect fit to play the arsonist suspected of killing Shay — a storyline that’s the basis for this week’s heavily promoted two-night event on the NBC first-responder dramas “Chicago Fire” and “Chicago P.D.”

RELATED: ‘Chicago Fire’ to revisit Shay with memorial, new footage

The Northwestern University grad and former Chicago stage actor recently returned to his old stomping grounds to film a guest star gig as a guy named Gish, a 47-year-old creepy creeper who’s been accused of arson in the past.

Knepper (“The Hunger Games: Mockingjay”) previously flexed his mean muscles as a carnie villain on NBC’s “Heroes.” He also did time as the evil Clock King on CW’s “Arrow” and “The Flash.” But he’s best known for his memorable turn from 2005 to 2009 as Theodore “T-Bag” Bagwell, a pedophile and white supremacist leader in “Prison Break,” the Fox drama that filmed its first season at Joliet Correctional Center.

Knepper in "Chicago P.D." | Photo courtesy NBC/Matt Dinerstein

Knepper in “Chicago P.D.” | NBC/Matt Dinerstein

“Fire” and “P.D.” showrunner Matt Olmstead used to have the same job on “Prison Break,” so he’s plenty familiar with Knepper’s ability to give viewers goosebumps.

“He’s one of the top three actors I’ve ever worked with,” said Olmstead, who cut his teeth as a writer for David Milch and Steven Bochco’s venerated cop show “NYPD Blue.”

“In terms of talent, preparedness and bringing something to the table you didn’t expect – something my old mentor David Milch would call ‘beating the page’ – he always exceeded your expectations,” Olmstead said. “On top of that, he’s a really good guy to have a beer with.”

A fan who knew I’d be interviewing Olmstead wanted me to find out whether the show’s scribes have their sights set on a specific performer when they craft a villainous role.

“We don’t,” Olmstead said. “We just go ahead and write the character and then Jonathan Strauss, who does casting for us, will submit names. I was on ‘Prison Break’ all four years. Jonathan knew that connection. When he submitted Knepper, of course I was like, ‘If you can get him that would be wonderful.’”

“Fire,” “P.D.” and “Law & Order: SVU” head honcho Dick Wolf has long relied on the New York-based Strauss to play Cupid when it comes to casting his shows.

“He comes up with very interesting people on a regular basis … Amy Morton [sardonic Desk Sgt. Trudy Platt on ‘P.D.’] being a perfect example,” Wolf said at the TV critics’ winter press tour in Pasadena, California. “She’s essentially the Meryl Streep of Chicago, and that was all Jonathan.”

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“The thing you hope for most in a casting director is that you have a shared sensibility,” Wolf added. “I’ve never put a DVD in and gone, ‘What the heck?’ And that’s happened in the past when it’s like, ‘Wait a minute: It was supposed to be a center on a basketball team and there’s a guy there who’s 5-foot-3.”

Olmstead liked Strauss’ idea of Knepper-as-arsonist so much, “I reached out to Rob trying to court him, which I rarely do,” the showrunner said. “He kind of half did me a favor and read the material. He liked it and was available. The stars aligned.”

It’ll be interesting to see which former “Prison Break” stars and writers would be available if the rumored reboot of that show comes to fruition. The new co-CEOs of Fox Television Group expressed an interest in resurrecting it at winter press tour.

“That show has a special place in my heart; it kind of launched my career,” said Olmstead, who met his wife, TV producer Dawn Parouse, when they both worked on “Prison Break.” “Everything about it was a home run. If they ever did try to revisit it, I’d be happy to go give my ideas and help whatever way I could.”

Except as showrunner.

Said Olmstead: “I’m a little busy these days, I’m glad to say.”

“Chicago Fire” and “Chicago P.D.” air at 9 p.m. Tuesdays and Wednesdays, respectively, on WMAQ-Channel 5.


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