Elizabeth Devine and Rich Cataloni spent 15 years working as criminalists in the Los Angeles County Sheriff's Department. They preserved crime scenes, analyzed blood-spatter patterns, helped solve murders with information derived from the tiniest samples of DNA. They didn't do O.J. -- Nicole Brown Simpson's body was discovered a few blocks out of their jurisdiction, falling instead to the LAPD -- but they had their share of famous cases. They worked the Menendez murders, in which brothers Lyle and Erik were convicted of the 1989 double-slaying of their parents. They also worked the high-publicity case involving Linda Sobek, the former Los Angeles Raiders cheerleader who was raped and killed in 1995 by photographer Charles Rathbun.

This did not make them cool. Not L.A. cool. Not Hollywood cool. Maybe high school reunion cool -- as in, Devine was declared to have the coolest career when she attended hers. And maybe backyard barbecue cool -- as in, people always wanted to hear about Cataloni's latest case when everyone was just hanging out. Descend into the nitty-gritty of it, though, and what Devine and Cataloni actually did was a little too abstruse to be hip in La-La land. They weren't cops, they weren't detectives, they weren't lawyers, passionately arguing cases in front of juries.

They were, by Cataloni's own definition, the "science geeks."

Enter television, and its power to transform public perception. Talk to network programmers these days -- or just look at the fall television lineups -- and it's quite clear that science is hip. Science is popular. Science grabs ratings.

And, as a result, the science geek resides in the same Zip code with the Hollywood chic.

"About 80 percent of this phenomenon can be summed up in three letters: 'CSI,' " says Robert Thompson, director of Syracuse University's Center for the Study of Popular Television. "The show has been so successful that all manner of people are borrowing from it. One of the things that makes it unique is that it has this kind of biological specificity. It's not like slasher gore, it's more like what you'd see if you were president of the science club. It's Quentin Tarantino merged with science class."

The CBS show "CSI: Crime Scene Investigation," which came on the air in 2000, is television's most popular drama and has spawned two spinoffs ("CSI: Miami" and, beginning Wednesday, "CSI: NY"). It also has prompted new fall offerings from other networks -- NBC's "Medical Investigation" and Fox's "House" -- that are trying to inject "CSI"-style, high-tech science into the medical show format.

To make these shows as technologically advanced -- and as technically accurate -- as possible, the networks are increasingly turning to the real experts. For "Medical Investigation," which is patterned on the Centers for Disease Control and Prevention (labeled the National Institutes of Health in the show), NBC has engaged the services of Don Francis, a 20-year CDC employee and an expert on infectious diseases. His previous experience with Hollywood? Matthew Modine played him in "And the Band Played On," a film about AIDS.

Devine had done a little consulting -- as in, explaining to film producers that nobody actually chalks around a body at a crime scene, showing where the yellow police tape would actually go, etc. -- but when she made the leap from the job in L.A. County to a full-time role at "CSI" in its first season, she was taking a major gamble. She had no idea the show would be as successful as it is, or that her role would include contributing to the writing and development of story lines (she's now with "CSI: Miami") in addition to consulting.

"You've seen a lot of my old cases on the show," says Devine, who was essentially a real-life Catherine Willows, the character played by Marg Helgenberger on the original "CSI." "A lot of the stories that I told the writers early on made it into episodes, either in bits and pieces or the whole thing. A lot of my life has been on that show."

Once "CSI" became a success, Devine brought her ex-colleague Cataloni (who now works directly with the writers in developing plots and implementing technology for the original "CSI") on board in her second year. She has since helped woo two other old office mates to the franchise: John Haynes, who now works on the Miami edition, and Bill Haynes (no relation to John), who is advising the New York version, which stars Gary Sinise and Melina Kanakaredes.

These are folks whose specialties once fell into the category of complicated science that confused jury pools. Cataloni, for example, is an expert in toxicology and firearms. John Haynes is a former homicide detective with a specialty in explosives. Bill Haynes is a DNA guy.

"Five years ago, when I had to go to court to testify, I had to tell people what a criminalist is and what my job is," Cataloni says. "Now people know, and they ask me stuff that indicates they probably know a lot about this stuff."

In the era of the O.J. trial, DNA testimony was still obscure to the lay person -- and thus somewhat incomprehensible to the jury. Now, pretty much anyone who has ever watched an episode of "Law & Order" is aware that someone's DNA can be typed off something as simple as a hair follicle, or an almost minuscule drop of blood.

The amazing advances that came with the introduction of the PCR (polymerase chain reaction, which can make a huge number of copies of a single gene) are old hat to most regular television viewers. They may not know what the equipment is, but they're well aware of DNA as a common investigative tool. So "CSI" strives to push the technological envelope.

"We come from a very large sheriff's department, the largest one in the world," Devine says. "We had a lot of the technology that you now see on the show available to us, which was nice. What you see on the shows, some of the labs don't have. But we had quite a bit of it.

"The technology is real and the science is real -- that's really our watermark," she says of the shows. "We do not make up the science. But we also want to be cutting edge so we look at what's new, and we use that."

And so in one episode, the "CSI" team uses a cyranose chemical vapor analyzer, a device that uses polymer composite sensors (geek alert!) to detect scent. The product is mainly marketed as an industrial quality control device to test for freshness or contamination, but "CSI's" techies and writers found a new use for it: In Season 2, Episode 1, they had it detect traces of a particular perfume, helping to find a killer.

"People love that stuff. I don't know that people are using that right now, but you could use it at a crime scene," says Devine.

People love that stuff, and so, too, do the cutting edge companies producing it. According to Cataloni, one company has given the crew a laser ablation ICP-MS (that would stand for inductively coupled plasma-mass spectrometer) -- which, in simple-speak, is a laser that can vaporize part of a tiny sample so its particles can be analyzed. In an upcoming episode, the "CSI" team uses it to extract a paint sample off of someone's fingernail.

"It's pretty wazoo science," Cataloni says. " . . . Some of the cool technologies that we have are not in the forensic labs in most of the country. They can't afford it. We can. We use ALS (alternate light sources), which are what make the cool lights on the show that make them put the glasses on when they're looking at stuff. We have more of those than the Los Angeles County Sheriff's office."

Or, as one of the cops says admiringly to Gil Grissom (William Petersen) in a first-season episode of the original "CSI:" "You guys have some toys."

The toy in question? "An electrostatic dust print remover," Grissom explains in the episode. "Like a super-charged lint remover, only it lifts footprints."

On "Medical Investigation" the gadgetry is not as sophisticated and specific as what is used on "CSI," though the emphasis on ramped-up medical technology is clear. Instead of showing intubations and surgical procedures in the style of "ER" or "Chicago Hope," "Medical Investigation" highlights the lab science that reveals the source of a patient's strange infection or bizarre illness.

"People are fascinated by modern science," says Francis, the show consultant, "but it's showing the application of modern science that is difficult. It's a different language, and translating that is the challenge."

And how do you make geek-speak digestible for the masses? One apparent solution is to bring in the geek to do the translation. Cataloni still remembers how everyone on the set -- the camera guys and the crew and anyone else within earshot -- was fascinated when he explained the how and why of a complicated technical scene to the actors early in his tenure with the show.

"That's one of the things that I'm proudest of, and that makes me happiest about the show," Cataloni says. "Liz and I used to be science geeks, and now we're kind of cool. Science is not like learning to speak ancient Greek. The show has made science cool."

The once-geeky science behind William Petersen's "CSI" probes has become cool."CSI" technical adviser Elizabeth Devine gives students a tour of the set. The science on the program "is real," she says. " . . . We do not make up the science."Gary Sinise examines a murder victim on "CSI: NY," which debuts this fall on CBS, expanding the franchise of the most-watched drama on TV.