A photo from “Immortality,” the “CSI” series finale, with William Petersen, Marg Helgenberger and Jorja fox. (Sonja Flemming/CBS)

“CSI: Crime Scene Investigation” arrived in October 2000 with a scream — The Who’s Roger Daltrey howling “Who Are You?” over the opening credits. It was a jaunty way to introduce the crack team of blood-spatter analysts, DNA experts and an entomologist who could determine a murder victim’s time of death from a beetle larva burrowed into a blunt-force trauma.

The graveyard shift of eccentrics, dweebs and one former stripper has provided audiences with salacious stories for the past decade and a half, but now it’s time for goodbyes. The Las Vegas-set series that made science sexy is going out with a bang — oh, literally: There will be explosives — on Sunday night with a two-hour movie finale.

Discerning critics won’t lament the “CSI’s” death. It wasn’t a “prestige” drama — hardly a Dickensian epic like “The Wire,” lacking the Shakespearean character arcs of “Breaking Bad,” drawing none of the fan-boy mythologizing of “Lost.” It was just splashy entertainment set in an otherworldly Sin City.

It worked. The show aced the Nielsen ratings, climbing to the top spot in the mid-aughts and spawning a billion-dollar franchise. But its brief heyday and handful of spinoffs (all canceled by now except for “CSI: Cyber”) aren’t its only legacies. This bagatelle of a diversion made a real impact, for better and worse.

What, exactly, you ask? Let’s follow the evidence.

1. Cops, cops and more cops

“CSI” premiered in a radically different TV landscape. Reality TV wasn’t a dominant force, and NBC was still riding high with its Thursday “Friends”/“Frasier”/“ER” blitz. The closest thing “CSI” had to an ancestor was “Law & Order,” which had debuted a decade earlier. The two shows had similarities — crime procedurals with ensemble casts and viewers just as likely to consume episodes in rerun form as on their regularly scheduled nights.

But “CSI” was distinct. If “Law & Order” strove for gritty realism (originally), the CBS hit was slick and stylized. “CSI” became an immediate sensation, and the copycats were close behind. “CSI” producer Jerry Bruckheimer was responsible for a few of them — “Cold Case,” “Without a Trace,” a handful of like-minded castaways — but there were so many others. Consider that in 2000 none of the Top 10 Nielsen-rated shows were crime dramas, but five years later half of them were: “NCIS,” “NCIS: Los Angeles,” “The Mentalist,” “Criminal Minds” and, of course, “CSI.”

2. Nerd love

“CSI” wasn’t just about cops fighting crime; it was about the science that leads cops to killers. The protagonists were hardly the cool kids. In the pilot, a couple of Vegas police officers watch as brainiac bossman Gil Grissom (William Petersen) approaches the crime scene. “Here comes the nerd squad” says one with contempt. (That line also encapsulates the show’s tendency towards laughably detailed exposition. The fear that a single viewer might be confused by the proceedings was forever palpable.)

The lab rats and techies clacking on keyboards and chanting “enhance” may not have been hip, but they were lovable. And suddenly science was trending. Interest in forensics skyrocketed, and TV reflected the shift with “Bones” and “Body of Proof,” and geeky series in other genres — “The Big Bang Theory,” “Chuck” and “Fringe.” Score one for STEM.

3. Cinematic television

“CSI” was Bruckheimer’s first major foray into television, and he brought the free-spending attitude that fueled his movies like “Bad Boys,” “Top Gun” and “Beverly Hills Cop.” The show was both flashy and moody, with major thought put into cinematography. There were stellar special effects — big-screen-caliber CGI, for example, to illustrate what happens when a bullet enters a body or a bone breaks (with the sickening sound evoked as well).

The delicious grossness of it all was enough to draw the attention of Quentin Tarantino, an A-list fan who agreed to direct the two-part finale of Season 5, “Grave Danger.”

4. The revolving door ensemble cast

“CSI” wasn’t the first show to see its actors come and go. Yet there was something noteworthy about the way “CSI” flaunted the expendability of its characters from the beginning. Within the first few episodes, rookie agent Holly Gribbs (Chandra West) — ostensibly a member of the regular cast — was killed on the job and replaced by Sara Sidle (Jorja Fox). Apparently, test audiences didn’t like Holly. Easy come, easy go.

There’s been no pretense of loyalty ever since. The template was always more important than the personalities, never more evident than when Fox and co-star George Eads tried to play hardball during contract negotiations in 2004 with a walk-out. CBS called their bluff by firing them. Both claimed it was all a misunderstanding, and the network rehired them. But the show still has had plenty of turnover, with Petersen leaving to be replaced by Laurence Fishburne and then Ted Danson; Marg Helgenberger exiting the series; Elisabeth Shue joining the cast; and Fox quitting and then returning a couple of seasons later. (Both Helgenberger and Petersen are returning for the finale.)

5. Misinformed jurors and smarter criminals

The impact of the “CSI effect” has been hotly debated, but at worst it means that jurors now fancy themselves forensic experts, thanks to the unrealistic abilities of Grissom and company. Prosecutors have complained that juries are less likely to convict if cash-strapped police departments haven’t done high-tech testing with fancy, newfangled technology, but the effect has been pretty anecdotal.

Meanwhile, any criminal with an antenna now knows that dousing a crime scene with bleach can destroy physical evidence. Thanks a lot, “CSI.”

6. An inescapable, never-ending loop of the Who

“Whooooo are you? Who? Who? Who? Who?”

Will we ever escape that song? The Pete Townshend-penned track that provided the show with a catchy opening gave the Who a boost that multiplied when spin-offs “CSI: Miami,” “CSI: New York” and “CSI: Cyber” all used songs by the band, too: “Won’t Get Fooled Again,” “Baba O’Riley” and “I Can See for Miles.”

7. Confirmation of Justin Bieber’s true nature

Bieber was one of many “CSI” guest stars over the years, a tribe that also includes Taylor Swift, Faye Dunaway, and a hammy, pre-fame Jeremy Renner. The Biebs’s 2011 guest spot happened to coincide with the release of his concert documentary, “Never Say Never,” which cast the pop star — prior to his subsequent tangles with the law — in a relentlessly angelic light.

But Helgenberger set the record straight in an interview on French radio. “He was kind of a brat,” she divulged before covering her mouth in faux-horror at her loose-lipped confession. Well, he was actually nice to her, she explained, but he locked a producer in a closet and punched a cake for some reason. What kind of monster ruins a perfectly good cake?

8. Exposure to fringey behavior previously unknown

“CSI” was all about shock value. Villains inevitably had some bizarre baggage: The chimera-like man whose DNA tested negative even though he really did rape and kill that poor woman, or the lady who stole people’s organs and blended them into smoothies to treat her porphyria.

The show also opened our eyes to a world of fetishes — and some sexual content that was extremely risque for prime time — including a recurring character who was a dominatrix, an episode that featured a plushy and furry convention, and — freakier still — the grown man who liked to dress up like a baby, diapers and all. It was terribly enlightening.