Zac Efron got his friends to ''spiritually cleanse'' him after filming his scenes as serial killer Ted Bundy.

The 30-year-old actor stars as the notorious figure, who confessed to having committed 30 homicides before his execution in 1989, in new movie 'Extremely Wicked, Shockingly Evil and Vile', and in order to regain his calmness, he got his pals to waft burning sage around him.

Asked how he coped with such an intense role, he said: ''I went and had some friends sage me. You know, do a little spiritual cleansing.''

The 'Baywatch' star says that it was ''fun'' to act out a real-life person, but says it's more of an ''experiment'' than a page-by-page account of Bundy's life.

He told 'Entertainment Tonight': ''It doesn't really glorify Ted Bundy. He wasn't a person to be glorified. It simply tells a story and sort of how the world was able to be charmed over by this guy who was notoriously evil and the vexing position that so many people were put in, the world was put in. It was fun to go and experiment in that realm of reality.''

Efron stars alongside 'Big Bang Theory' star Jim Parsons as Larry Simpson, the lead prosecutor in the 1979 Miami trial that convicted Bundy of his crimes.

Other cast members include Lily Collins, who was cast as Bundy's girlfriend Elizabeth Kloepfer, and Kaya Scodelario as his ex-wife Carole Ann Boone, with whom he had a lasting relationship with up until the trial which saw him sentenced.

John Malkovich stars as Judge Edward Cowart, who presided over the 1979 trial, and Angela Sarafyan and Grace Victoria Cox are also in the movie.

The film - directed by 'Paradise Lost: The Child of Murders at Robin Hood Hills' filmmaker Joe Berlinger - will tell the shocking true story of Bundy, who raped and murdered numerous young women during a killing spree in the 1970s that shocked America and the world.

Bundy chose to represent himself at the trial, which was broadcast on national television, and appeared to develop something of a rapport with the judge.

The script has been written by Michael Werwie and is thought to explore the crimes of the killer through the eyes of Bundy's girlfriend.