But the film itself, which wasn’t screened for critics before opening day, would have been horrendous anyway; place any other actress in the part and it’s just another straight‑to‑DVD release.

Lohan stars as both Aubrey, an aspiring writer who goes missing, and Dakota, an exotic dancer who wakes up in the hospital with parts of her right arm and leg sawed off. Investigators (Garcelle Beauvais‑Nilon and Spencer Garrett) searching for a possible serial killer and even Aubrey’s parents (Neal McDonough and Julia Ormond–you read that right, Julia Ormond) swear the girl is Aubrey. She keeps insisting she’s Dakota.

Does she have amnesia? Is she delusional? Or maybe she’s identical twins, and this is “The Parent Trap” with pasties.

(Just so we don’t get confused, director Chris Sivertson has imposed an easy‑to‑follow, overbearing color scheme. The Lohan‑as‑Aubrey segments are drenched in cobalt blue, from her convertible Lexus to the gag that’s placed in her mouth as she’s being tortured; for Lohan‑as‑Dakota, everything is red, including the bras and bustiers she wears on stage. So helpful!)

But it’s tough to get engrossed in any mystery Sivertson is trying to achieve, working from a script by first‑timer Jeffrey Hammond, because so much of what Lohan is called to do is a distracting reminder of her off‑camera misadventures. Performing on stage as Dakota, she leans up against a pole and slides down it, eyes closed, mouth open, head tossed back. And you’re watching her thinking: Where have I seen that before? Oh, yeah. That looks just like the photograph of Lohan sitting passed‑out in the passenger seat of a car after a long night of partying.

Dakota/Aubrey is being held in a hospital against her will. She gets driven home in a cop car. And then there’s the high‑tech prosthetic leg she has to wear, which beeps when its battery is low. You can’t help but be reminded of the clunky ankle bracelet Lohan received after her second stint in rehab–you know, the one that was designed to detect alcohol consumption.

Even if you could ignore all that, there’s nothing even remotely scary or suspenseful about “I Know Who Killed Me.” Ridiculous is the word that more often comes to mind, especially during the scene in which Dakota loses a finger while taking off one of her full‑length red gloves, then tries to reattach it on the bathroom sink using duct tape and string. And we haven’t even mentioned the sex scene with Aubrey’s boyfriend (Brian Geraghty) that’s played awkwardly for both titillation and laughs.

It makes you wonder what Lohan was thinking when she said yes to this project. Despite her frequent appearances in the tabloids, she seemed to be making the transition nicely from charismatic Disney darling to a young actress who wanted to be taken seriously, with small roles among prestigious ensembles in “A Prairie Home Companion” and “Bobby.”

You want to know who killed her? She’s doing it to herself.

“I Know Who Killed Me,” a TriStar Pictures release, is rated R for grisly violence including torture and disturbing gory images, and for sexuality, nudity and language. Running time: 105 minutes. One star out of four.