The potential for fan-favorite characters to share their fictional universes is catnip for the imagination. But some fandoms have it easier than others, and The X-Files links up with the Law & Order universe in a way that's too neat to ignore. With guest star Richard Belzer reprising his Homicide: Life on the Street character Detective John Munch several years before his transfer to Law & Order: SVU, it's simple to make the argument that, hidden behind a world of Lennie Briscoe and Olivia Benson, there's an alien conspiracy meant to re-colonize the human world.
"Unusual Suspects" is the 100th episode of The X-Files, and it's a love letter to the series' themes of conspiracy and paranoia. It's the first episode to feature The Lone Gunmen as the protagonists, with agents Mulder and Scully pushed to the back burners. As it opens, a SWAT team sweeps a warehouse in Baltimore in 1989, flushing out The Lone Gunmen -- John Fitzgerald Byers, Melvin Frohike and Richard Langly -- as they attempt to flee and eventually recovering a hallucinating Fox Mulder. The rest of the episode is told in flashback, as Detective Munch braces Byers, the bearded leader of the trio, in an interrogation room.
Byers' story isn't just a wild ride of assumed identities and secret weapons programs meant to terrify and control a civilian populace. It's also the story of how the three conspiracy theorists become friends and even meet Agent Mulder years before the series proper. But none of it lands with the stony-faced Munch, who, ironically having his own love for conspiracy, is ready to leave the Gunmen in a jam until Agent Mulder backs up Byers' story.
The episode wasn't initially conceived as a crossover with the cult favorite cop drama. As recounted in Andy Meisler's Resist or Serve, the official X-Files fifth season handbook, once writer Vince Gilligan realized his script was centered around a Baltimore detective, it seemed natural to reach out to Homicide's showrunners. Tom Fontana, the drama's producer, was only too happy to agree. Detective Munch had already crossed over with Law & Order, and even made his second appearance on the show only four days before "Unusual Suspects" aired.
When Munch transferred to New York City and the Special Victims Unit in 1999, he kicked off an unusual legacy of chaining franchises together, even across networks. Though Law & Order's usual fare avoids the conspiratorial -- save for a 2017 episode that investigated a fringe theory -- there's nothing to say Munch's day in a Baltimore warehouse isn't still part of canon. As part of a federal investigation touched by the hand of the infamous Cigarette Smoking Man, Munch might chafe under threats and gag orders, but the CSM had a way of making people either abide by his demands or disappear.
Munch remained a grouchy, untrusting detective until the end of his police service, but was always just as full of heart. Dogged and reliable, his occasional lurch into dramatic weirdness was a part of him. It's a character motif that made him a natural fit for life in the X-Files universe, even if just for a moment. Though confirming that moment as canon is probably too much to ask, it would be a lesser universe for both franchises without Munch's strangest day on the job.