After earning an Oscar nomination when she left Las Vegas, Elisabeth Shue is returning as that city’s newest forensic sleuth.

Fictionally, that is. Known not only for “Leaving Las Vegas” but such other movies as the original “Karate Kid,” “Adventures in Babysitting” and the two “Back to the Future” sequels, the actress admits she’s stayed low-key with many of her recent projects. That changes in a big way when she joins the globally popular drama series “CSI: Crime Scene Investigation” Wednesday on CBS.

“It’s going really well,” Shue says of her first weeks on the “CSI” job, “and I’m very, very grateful that I have Ted Danson to work with. I’m just starting to work with the other cast members, but I’ve primarily started out working with him. He’s such a wonderful actor and so easy to be around ... and very present in his work, which I always appreciate more than anything. We’ve been having fun.”

Shue comes into the series’ 12th year as Julie “Finn” Finlay, who has a history with current Vegas forensic lab chief D.B. Russell (Danson). He needs her help on a case involving the murder of a man’s ex-girlfriend, but she’s reluctant because of her earlier working relationship with Russell: He fired her. Consider that she’s also just taken anger management training, and fireworks are bound to begin soon.

Though she has appeared on HBO’s “Curb Your Enthusiasm,” it’s been almost 30 years since Shue – the sister of former “Melrose Place” regular Andrew Shue – last co-starred in a series, the acclaimed ABC Air Force-family drama “Call to Glory.” Some have labeled her a “replacement” cast member on “CSI,” given Marg Helgenberger’s very recent exit, but Shue doesn’t see it that way.

“I didn’t get to meet her, even,” she says. “She had left maybe a month before I came onto the set. I don’t think I’m replacing her at all; no one can ever replace any actor, every one is so unique. I just feel like this is a new character who happens to cross paths with this world.”

To operate within it, Finlay has to deal with her share of corpses. “I thought I would be” queasy about tackling such scenes, Shue allows. “I did have an initiation at a crime lab in L.A. and also at the coroner’s office. I got to watch an autopsy and be with many dead bodies, and that was so intense ... really profound. I really recommend it to everybody, just to value your own life, and to appreciate and be grateful for every moment. I felt like I could have passed out.

“I was breathing very heavily and deeply,” Shue adds, “but as time passes, you get used to it. You realize the body is not the person, but the vessel. You almost start to disassociate with it being a human being, and it becomes easier. I think that’s what the job of the CSIs involves. I’m sure there are times when they get too close to the humanity of it all, and it’s probably overwhelming.”

Even if she wasn’t becoming the female lead in an established franchise, Shue would be cautious about any series offer. “I always overthink every decision and make them huge,” the mother of three muses, “but the timing of this is perfect for my life. In the past, whenever I was offered anything like this, I could never imagine leaving my 5-year-old. The thought of doing that for too long was unbearable, so doing one-independent-film-that-no-one-ever-saw per year was plenty.

“I was more than happy to go off and work in obscurity, then this presented itself.”