BY RICHARD ROEPER | SUN-TIMES MOVIE COLUMNIST

The lowest form of human being on the planet is the man or woman who takes another life — and yet some killers become despicable rock stars of a sort.

Ted Bundy is far better known than any of his victims. Charles Manson is world-famous. Scott Peterson and Joran van der Sloot have received multiple marriage proposals. Lyle Menendez was married on the day he was sentenced for the murder of his parents, eventually was divorced and has since married ANOTHER prison groupie.

Sick.

James Franco taps into that unsettling mindset with his compelling performance as the conniving and manipulative albeit charming sociopath Christian Longo in “True Story,” which is indeed based on a true story about one of the more bizarre journalist/defendant alliances in modern annals.

Directed with detached style by Rupert Goold, “True Story” begins where a conventional crime thriller would end: the arrest of Christian Longo in Mexico. Accused of murdering his wife and three young children in unspeakably gruesome fashion, Longo had been on the run and posing as New York Times journalist Michael Finkel.

Franco’s pal and sometimes partner in comedy Jonah Hill plays Finkel, a gonzo superstar journalist who flamed out in spectacular fashion after it was discovered his New York Times Magazine cover story on the abuse of workers on cocoa plantations in West Africa contained egregious errors and misrepresentations.

After Finkel is fired, he retreats to a log cabin in Montana, where his girlfriend Jill (Felicity Jones) stands by her man as he desperately tries to land freelance work, even though he realizes he’s an utter pariah and his career could be over.

Then comes the call. A journalist from Portland wants to interview Finkel about Christian Longo, who is now in custody and will stand trial for the heinous murder of his wife and children. This is the first time Finkel learns about Longo’s inexplicable decision to take on his identity. It’s unsettling, to say the least — but Finkel also seizes the opportunity for a possible career comeback. If he can get Longo to talk to him, it will be a huge exclusive. Maybe even a book.

Much of “True Story” is staged like a two-character play. It’s just Finkel and Longo in an interrogation room in prison, forging an unlikely and somewhat creepy bond as the Finkel tries to get Longo to talk about the crimes, and Longo spins stories and dances around the truth and flatters Finkel by praising his writing and asking him about his wonderful girlfriend.

At times the dialogue is too obvious and heavy-handed, hammering home points we’ve already discerned. A few scenes in the cabin are overwrought. Jill is horrified by Longo’s drawings and my Michael’s growing fascination with Longo. We get it. We don’t have to be reminded of it time and again. (Jones is brilliant in a scene where Jill confronts Longo in prison and tells him exactly who he is, but it’s far too theatrical and almost too perfectly written. It plays more like wish-fulfillment than something that actually took place.)

Franco gives one of his best performances as Longo. There’s never a false note. From the get-go, we’re almost positive this man is a stone-cold murderer, and yet we understand how Finkel could be seduced into thinking that maybe, just maybe, someone else did it.

Hill doesn’t try to turn Michael Finkel into a hero. His eyes blinking madly behind his thick glasses, Michael is usually the smartest person in any room — but he’s not smart enough to try to hide that. Even after his fall from grace, he can barely contain his hubris. It’s a wonder the lovely and smart and patient Jill puts up with him.

The courtroom scenes are unapologetically over-the-top and sometimes excruciatingly exact in the details of the

murder, but you won’t soon forget Franco’s expertly nuanced performance. It’s as good as any work I’ve seen in a film in 2015, and “True Story” is one of the better movies to come along this year.

‘TRUE STORY’

[s3r star=3.5/4]

20th Century Fox presents a film directed by Rupert Goold. Written by Michael Finkel and Rupert Goold. Rated R (for language and some disturbing material). Opening today at Landmark Century and Landmark Renaissance.