When Jorja Fox’s Sara Sidle steps back into the Las Vegas crime lab in the series premiere of “CSI: Vegas,” she can’t help but marvel at what she sees. It is an experience shared by Daniel Holstein, the series’ technical advisor and a retired crime scene analyst.

Holstein says that technological advancements in the last few years have done wondrous things for forensic tools, everything from DNA testing and phenotyping to the accessibility, speed and portability of essential equipment. Holstein was the inspiration for “CSI’s” cornerstone character of Gil Grissom (William Petersen), and he worked as a consultant on the original “CSI: Crime Scene Investigation” procedural that became a sleeper smash in its fall 2000 debut on CBS.

“I’ve used scanning electron microscopes before that took up half a room. When I saw this device — you’re talking maybe 2 feet by 3 feet by 3 feet in height; it’s a little box,” Holstein tells Variety of what up-to-date crime labs, and therefore “CSI: Vegas,” use.

Additionally, he notes, “since 2017, there have been a lot of studies on blood stain aiding — when did bloodletting occur? They’re perfecting the science in terms of peaks that come out on the screen, and knowing where to look for that peak will give you a range of when bloodletting occurred [from] three weeks ago, plus or minus two or three days, ranging all the way up to years. And that is something that is very new.”

It is not only the tools that have evolved over the span of “CSI’s” original 2000-2015 run to the Oct. 6 premiere of “CSI: Vegas.” The conversations around both law enforcement and science, individually, have become heated over the last few years.

Development on “CSI: Vegas,” the latest iteration of the franchise, began in February 2020, before “defund the police” became a rally cry at mass demonstrations following the murders of George Floyd, Breonna Taylor and others. That was also before the COVID-19 pandemic became headline news, bringing about dissonance over mask-wearing and vaccines. Premiering in a landscape where both of these things are top of mind for viewers may put a little more pressure on the storytellers, but it is a pressure the characters also feel and must respond to over the course of the episodes.

“I wanted to tell a story about heroes that do the nitty-gritty and don’t look at science as perceived wisdom from a preferred news outlet but instead as a method. There’s a rigorous approach you can get to derive the truth from first-hand evidentiary experience and data collection. That’s why I felt the show belonged on the air in 2021,” says showrunner Jason Tracey. “Our characters want to live up to and restore public trust, and it’s a joy to write characters that are heroic, as opposed to anti-heroic at this point in time, and showcase how we’d all like to see it done — to solve it scientifically as opposed to breaking down doors and knocking heads.”

The “CSI: Vegas” premiere draws Sara (and eventually Gil) back into the fold when one of their former teammates is accused of fabricating evidence, calling into question the validity of hundreds of forensic samples and giving cause for many convicted criminals to want their cases reopened. Whether that person is guilty or is being framed is a big part of the first few episodes of the season, Tracey previews, noting that they “turn the corner at the top of the season and a new question emerges as to who might be manipulating the story around this investigation.” Suddenly, every move made by anyone currently working in the crime lab is under a microscope.

“We wanted our villain of the season to be operating in the shadow, casting doubt, because that’s what’s out there. We are at a point where the barrier for entry is lower for pulling off some really impressive and nuanced crimes. What you can do with a 3D printer is pretty terrifying, whether it’s make a weapon or falsify a fingerprint. The technology exists in people’s hands, you can do video editing, you can send a virus, it’s pretty unbelievable and it would have been unthinkable, even at the height of the (original) show,” says Tracey. But, “the ethos of the show was always about the rigor that these people bring to the job. And I think that more than a claim that science is facts, it’s a process; the specific method is the thing that’s going to bring you to the truth. So, you don’t have to take someone’s word for it when they recite something they claim is a fact. By doing the process right, you can trust the results of the rigor of their analysis.”

A common refrain on “CSI” was to “follow the evidence,” as it followed the team of forensic scientists working at the Las Vegas crime lab. The same mantra is how Maxine Roby (Paula Newsome) runs her department now on “CSI: Vegas.” But although the faces and some of the gear have changed, the science has not. Holstein points out that fingerprint analysis, for example, can be run through a machine to narrow down matches, but it will always have to be finalized by the human eye because “a lot of fingerprints have distortion, and the machines are taking into consideration the width of the ridge, the distance between the minutiae, but can’t account for the distortion.”

In order to depict the science as accurately as possible, Tracey says his writers’ room would “try to get ideas in front of Daniel as early as possible.” Holstein would give detailed script notes, looking for the proper terminology in the dialogue, as well as making sure there was a correct explanation for how each piece of equipment needed to be handled — down to as basic as how it’s turned on.  The one area the show did have to lean toward story over reality at times was with the speed at which certain test results come back. Holstein says real-life forensics has come a long way, recalling the days he was on the force and a DNA sample took six weeks for analysis, but the early episodes of the new season still required some liberties with time.

Gas chromatography–mass spectrometry (GCMS) testing, which detects and identifies substances on materials, “can take up to days to prepare, to get things ready, for the machines to go through all the samples and so forth,” he says. But on the show, they often need everything one in one day.

Tracey adds that occasionally in production, in order to make a chemical test pop they would “fudge” the color as well. “But I don’t know that that’s really betraying the science. You’re still getting the answer you would get with the science,” he says.

Tracey remembers learning a lot about epithelial cells and blood spatter from the original “CSI,” so he knows the audience of his show will have much of that knowledge, too. Still, he feels it is important to salt the characters’ dialogue with specific brand names and terms — such as a “portable Raman spectrometer” — for general context because the nitty-gritty of the science of forensic inquiry is intrinsic to fabric of the show.

“I’m not going to write a better line than the truth,” he says.

“CSI: Vegas” premieres Oct. 6 at 10 p.m. on CBS.