Transcript for Ted Bundy movie faces backlash for allegedly glamorizing serial killer
Reporter: He was perhaps the most notorious serial killer in American history, Ted Bundy, a psychopath known as much for charisma as his heinous crime. He doesn't look like the type to kill somebody. Did you do these things? Absolutely not. Reporter: And now the movie is sending shockwaves. Zac Efron portraying the sinister killer who used his own attractiveness to lure more than 30 women before brutally murdering them. ? Ladies and gentlemen, I am that innocent suspect. You are skating on thin ice, partner. Reporter: Now it is gaining criticism. You see him smiling, kissing women. It is a sexy, attention grabbing trailer. Reporter: They denounce the promo for making Ted Bundy hypersexualized. He was known as a charming, charismatic guy. That is why he was cast. Reporter: The preview's release coincide's with the biopic's debut at sundance. Efron known for wholesome roles in "High school musical" and "The greatest showman." Taking on his darkest character yet. I think he's a fascinating individual. This is a great movie for a hard lesson to learn. Reporter: Despite the controversy over the trailer, some who've seen the film in its entirety say it's a fair depiction, calling it honestly unsettling and a fine, smartly-structured screenplay. What's it like for somebody to actually be guilty like Ted Bundy, but everyone around them is so charmed that they think he's innocent? Reporter: Joe burlinger directed the biopic and spoke about Efron's casting before the outcry. In many ways we are take his teen heartthrob image and turning that on its head. We're understanding why women were so attracted to this charismatic killer through Zack's performance. Reporter: And since the controversy, the director saying the film in no way glorifies Bundy or his atrocious acts. Our film is a serious portrait of how he deceived the people closest to him. And his manipulation of the American media allowed him to flourish. Burlinger who spent his career focussing on criminal justice reform has now directed the new docuseries "Conversations with a killer." The Ted Bundy tapes with these never-before heard audiotapes. Where that psychopathic charm was on full display. I think things are going to work out. That's about all I can say. Good evening. I'm Ted Koppel and this is "Nightline." His name is Theodore Bundy. He's confessed to 20 killings and is suspected in at least 16 more. Reporter: Ted Bundy went on a trail of terror in the '70s. Protected from me and others like me. Reporter: Wooing young women, kidnapping, raping and killing at least 30, dismembering some. A lot of times, he would want them out cold. So if they were out cold, he could do whatever he wanted to do. Reporter: Bundy's homicidal rampage spanned at least seven states. People in one county tended to work in their county. They didn't talk to the next state over or two states over. So as a result, he was able to evade being identified for such a long period of time, in effect, because law enforcement really wasn't sharing information with each other. Reporter: In 1975, Bundy was finally arrested and later convicted of kidnapping but escaped police custody twice. A few years later at this Florida sorority house he killed. He felt no matter what he did that he was smarter than all of them. Reporter: His televised murder trial where he acted as his own attorney attracted millions of women. Before his death, Bundy finally confessed to more than 30 murders, although the true number of his victims may never be known. For everything that he did to the girls, the bludgeoning and the strangulation, I feel that the electric care is too good for him. Reporter: He was executed 30 years ago last week, but his infamy lives on. He defied stereotypes and became a media star. He knew how to manipulate the media. And more importantly, his murder trial was the first nationally-tell advised trial. Bundy made serial murder mainstream entertainment pause
This transcript has been automatically generated and may not be 100% accurate.