It was written by Vince Gilligan and directed by Kim Manners and it originally aired in the United States on November 16, 1997 on the Fox network.

The episode earned a Nielsen household rating of 13.0, being watched by 21.72 million people in its initial broadcast and received mixed to moderately positive reviews from critics.

The show centers on FBI special agents Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson) who work on cases linked to the paranormal, called X-Files.

"Unusual Suspects", however, functions as a flashback episode: in 1989, two salesmen and a federal employee join forces when they meet Susanne Modeski, a woman who claims that she is being pursued by her supposedly violent ex-boyfriend, an FBI agent named Fox Mulder.

The concept for having an episode dedicated to The Lone Gunmen arose when the show's producers were forced to start production of the fifth season in the last week of August in Vancouver, but still needed series stars David Duchovny and Gillian Anderson for the filming of The X-Files movie in Los Angeles.

Writing duties fell to Vince Gilligan, who initially drafted a story about nanotechnology, before changing to the origins of The Lone Gunmen on behest of series creator Chris Carter.

In addition, "Unusual Suspects" serves as a cross-over with the NBC series Homicide: Life on the Street, featuring Richard Belzer's Detective John Munch character.

When Byers bumps into the woman, she introduces herself as Holly and claims that her daughter had been kidnapped by her ex-boyfriend, who is in the Baltimore area.

Frohike convinces Byers not to turn himself in, and recruits Langly to help them hack into the FBI database to learn more about Holly.

They discover that "Holly" is actually Susanne Modeski, who is wanted for acts of murder, sabotage, and terrorism at a weapons facility in New Mexico.

The idea for "Unusual Suspects" arose when the show's producers were faced with a dilemma in August 1997: Fox demanded that they begin production on the fifth season of the show, but series co-stars David Duchovny and Gillian Anderson were still working on The X-Files movie in Los Angeles, and would be unavailable until the start of the next month.

Staff writer Vince Gilligan was assigned to pen the episode, and he initially drafted a story involving nanotechnology, which series creator Chris Carter vetoed for fear that it would squander possibly the show's one chance to showcase the Gunmen.

But then Vince, who loved the characters and really wanted a chance to dig more deeply into them, created a back story and they became a lot more interesting.

"[2] Actor Dean Haglund, who played Langly, said of the episode, "What we read in the script wasn't really our origins as we'd imagined it.

[2] When writing the episode, Gilligan lobbied for it to be a crossover with the NBC show Homicide: Life on the Street, which also takes place in Baltimore.

'"[3][4] Despite some hesitancy from Fox's lawyers, NBC's executive producer Tom Fontana was eventually contacted, and he was more than willing to allow the use of Belzer.

Manners was inspired by the 1939 film adaption of The Wizard of Oz, more specifically the image of "the Scarecrow, and the Tinman, and the Lion ... shaking behind Dorothy.

Club reviewer Emily VanDerWerff gave "Unusual Suspects" an A−, and wrote that the episode "is a love letter to the very idea of paranoia".

[9] Furthermore, VanDerWerff argued that "as the episode moved its way to its climax, when Mr. X improbably lets the Gunmen live after seeing as much as they did ... it struck me that what we're seeing here may not entirely be meant to be taken seriously, just as 'Memoirs Of A Cigarette Smoking Man' [sic] is more about who the CSM wished he might have been than the person he actually was.

"[9] Robert Shearman and Lars Pearson, in their book Wanting to Believe: A Critical Guide to The X-Files, Millennium & The Lone Gunmen, rated the episode three stars out of five.

[10] Shearman and Pearson criticized the episode for being "largely concerned in suggesting to the audience that the government is being conspiratorial ... five seasons into a hit series which has turned that argument into a cliche.