If you know what a pyrolysis gas chromatograph-mass spectrometer does, can readily identify the symptoms of arsenic poisoning, and perk up whenever you hear the name Dr. Henry Lee, you’ve clearly been watching Forensic Files. Since its premiere 20 years ago on April 21, 1996, the documentary-style science series has guided television audiences through the often complex world of forensic science, and left a trail of network crime shows in its path (see: CSI).

To celebrate the beloved series’ 20th anniversary, we spoke with creator/executive producer Paul Dowling, who shared 15 fascinating facts about Forensic Files.

1. IT WAS CONCEIVED AS A TRUE CRIME VERSION OF THE “WHODUNIT” FORMAT.

“There was no particular case or incident that sparked the idea for the series,” Dowling tells mental_floss. “It was a new idea for how to tell true crime stories. Before Forensic Files, true crime TV series and documentaries were all produced in the same tired way, but fictional crime drama was excellent and getting much higher ratings. So why not marry the best of both?”

By melding talking head interviews with reenactments of both the crimes and forensic processes scientists used to solve said crimes, Dowling came up with a totally new type of television series. “I simply took the murder mystery 'whodunit' format of the successful fictional television crime dramas and used it to tell true crime stories,” he says. “That's how Forensic Files was born.”

2. IT WAS ORIGINALLY GOING TO FOCUS ON MEDICAL INVESTIGATIONS.

Longtime fans of Forensic Files might remember that it was called Medical Detectives in its earliest days. “Originally, we planned to tell not only murder investigation stories but also disease outbreak and accident investigations,” Dowling explains. “Over time, ratings showed that viewers preferred the murder mysteries, which explains the title change in 2000.”

3. THE PREMIERE EPISODE HAD A CONNECTION TO FARGO.

Spring of 1996 was a big season for death by wood chipper. In March, one month before Forensic Files debuted, the Coen brothers’ critically acclaimed black comedy Fargo was released in theaters. Among the film’s most memorable scenes is one in which Gaear Grimsrud (Peter Stormare) feeds the body of his partner, Carl Showalter (Steve Buscemi), into a wood chipper. The scene was inspired by the murder of Helle Crafts, who was killed by her husband, Richard, then disposed of in a wood chipper. Crafts’s murder was also the subject of Forensic Files’ very first episode, “The Disappearance of Helle Crafts.”

4. THE O.J. SIMPSON CASE HELPED BOOST THE SHOW’S POPULARITY.

It was only about six months before Forensic Files premiered that nearly 100 million people tuned in to see the verdict read in the O.J. Simpson murder trial. For many of those same courtroom watchers, it was the Simpson case that first introduced them to the basics of forensic science, which led to a built-in audience for Forensic Files from the get-go.

“The Forensic Files pilot of the famous Wood Chipper Murder case did indeed benefit from the wall-to-wall coverage networks had given to the O.J. trial,” Dowling says. “It prepared the public to handle crime scene photographs, detailed crime creations, and it gave audiences a good preview for the new role forensic science would play in the criminal justice system.”

5. THE SERIES BROUGHT ATTENTION TO LITTLE-KNOWN CASES THAT FEATURED BREAKTHROUGHS IN FORENSIC SCIENCE.

While Forensic Files didn’t completely shy away from revisiting well-known cases, it was in the lesser-known crimes that they were able to feature some truly groundbreaking scientific developments.

“We've done several one-hour specials on high-profile cases like the Kennedy assassination and Lindbergh baby kidnapping, but virtually all of the half-hour episodes (400 in total) were little-known [stories],” Dowling says. “Interestingly, many of the breakthroughs in forensic science happened because of the innovation and discoveries of scientists and investigators in these little-known cases, which we brought to worldwide audiences for the first time.”

6. PETER THOMAS WAS THE “FIRST, LAST, AND ONLY CHOICE” FOR A NARRATOR.

It’s impossible to talk about Forensic Files without mentioning the familiar voice that narrates each episode. That voice belongs to Peter Thomas, a world-class orator who has spent more than 50 years lending his pipes to Oscar-winning documentaries, television series, and commercials. For Dowling, Thomas—who passed away on April 30—was the only choice to serve as Forensic Files’ narrator.

“When the series was set to premiere in 1996, it wasn't going to look like a PBS or A&E crime documentary," he says. "It was going to be something new and different, a little ‘tabloidy,’ but I didn't want the series to sound like a tabloid, which I'd describe like an AM radio announcer doing a car commercial.

“I wanted the series to have the legitimacy of a documentary, despite how it looked, so I wanted a traditional voice, a great storyteller, classy, and chose a man whose voice was well known because he'd done some PBS documentaries and science and history films we'd all seen over the years in high school. That was Peter Thomas, my first, last, and only choice.”

7. THOMAS DIDN’T TAKE THE GIG LIGHTLY.

In a tweet, Dowling shared that, “Peter Thomas rehearsed each script for several hours the night before the recording session with his wife Stella as his audience.”

8. PRODUCERS ACTIVELY SOUGHT OUT “OMG” MOMENTS.

When asked if there were specific elements that made a case Forensic Files-worthy, Dowling says that, “It was the 'oh my god' factor. If a story had that, it was chosen.”

Some examples, according to Dowling:

"A doctor accused of rape implants a tube of his patient’s blood into his arm so the blood sample drawn for his DNA test wasn't his—and therefore, didn't match the semen sample from rape test kit. But the victim stole the doctor’s Chapstick and the DNA from those skin cells did match! The victim solved her own crime.

A killer in bare feet steps on a hamburger roll on his way out of the crime scene, leaving his clear footprint in the soft dough!

A piece of chewing gun found next to a dead body matches the teeth impressions of the suspect.

A sundial analysis proves that the time clock on a home video—the murder suspect’s alibi—was not correct, and had been doctored."

9. STUPID CRIMINALS DON’T MAKE FOR GREAT TELEVISION.

Some of Forensic Files’ most compelling episodes are the ones in which a crime is so sophisticated, and so well covered up (like the aforementioned doctor inserting a vial of his patient’s blood), that they make truth seem stranger than fiction. As for crimes that didn’t interest the producers? “Stories we rejected were often ones where a killer was so stupid, and left so much evidence, it was almost a comedy,” Dowling says.

10. THE REENACTMENTS LOOK DIFFERENT ON PURPOSE.

The show is generally made up of three different parts: interviews with the people involved, then reenactments of both the crime and the lab processes—each of which was filmed in a slightly unique style, which was a very conscious decision.

“I wanted to make sure viewers knew exactly what was reenactment and what was real crime scene video or authentic police interrogation footage,” Dowling explains. “We did that by setting recreations apart from the other elements by giving them a different look and using loud sound effects and flash frames and music bumps.

“Some crime TV series today try to make recreations seamless, so viewers can't tell what's real and what's not. I find that very confusing and, frankly, unfair to the accused.”

11. THEY TRIED TO CAST REENACTMENT ACTORS WHO RESEMBLED THE REAL PEOPLE.

“We used crime reenactments at the end of each episode to show how the scientific evidence put all the pieces together for prosecutors in the courtroom,” Dowling says. “When doing that, we tried to cast actors who looked as much like the individuals involved in the case as possible, to avoid confusing the viewers. Viewers obviously knew these were crime recreations intended to put all the pieces of the investigation puzzle together and were willing to suspend disbelief if and when the casting matches weren't perfect.”

12. THE ACTOR WHO PORTRAYED LEE HARVEY OSWALD LOOKED A LITTLE TOO MUCH LIKE LEE HARVEY OSWALD.

For the hour-long JFK special, it was particularly important to senior producer Kelly Martin that they cast actors who shared a strong resemblance to the real-life figures they were portraying. “We want exact matches or it is not going to work," Martin told The Morning Call in 2004. “This is one of the highest-profile killings ever. Pardon the pun, it had to be dead-on.”

They found their Lee Harvey Oswald in an actor named Marcus Hinkle, who may have looked a little too much like Oswald for some. “Martin said that when the company was shooting the JFK special on Sixth Street in Allentown, [Pennsylvania] last year, older bystanders who lived through the assassination said Hinkle gave them chills because he resembled Oswald so closely,” wrote The Morning Call.

13. MANY OF THE POLICE OFFICERS AND PARAMEDICS YOU SEE ARE REAL.

In 2004, Laurie Bianco—president of Pro Model & Casting Agency, the company tasked with finding the right reenactment actors for Forensic Filesexplained to The Morning Call that when casting on-screen police officers and paramedics, she preferred to use real professionals in those fields, because they behaved much more naturally in those parts.

14. IT HOLDS SOME TELEVISION RECORDS.

First, according to Dowling, “Forensic Files is the longest running non-scripted series in TV history.” In addition, the show “made television history in 2002 when it aired on NBC as a summer replacement series,” he says. “It was the first TV series that originated on a cable network first, before moving to a broadcast network airing new episodes.”

And its popularity stretches far beyond American borders. “At one time,” Dowling says, “Forensic Files aired simultaneously on five different broadcast networks at the same time in Great Britain: CBS Reality, UKTV, History Channel, Sky Network, and Discovery.” The series has been seen in 142 countries.

15. THERE’S AN OFFICIAL COMPANION BOOK TO THE SERIES.

In 2004, Dowling published The Official Forensic Files Casebook, which provides recaps of the series’ individual episodes, gives some behind-the-scenes details on how the show itself is produced, and offers further insight into why particular stories make the cut, and why others are rejected. (You can purchase it here.)

All images courtesy ForensicFiles.com