The actor, 30, looked nearly identical to Bundy in a green turtleneck and grown-out, curly hair. He even completed the transformation with ’70s style side-burns.
The upcoming thriller will chronicle Bundy’s crimes from the perspective of his longtime girlfriend Elizabeth Kloepfer, portrayed by Lily Collins.
Efron has been chronicling his time on set while filming, posting several behind-the-scenes photos to his social media.
“Schemin,” he captioned a recent shot.
He also showed off Bundy’s Volkswagen Beetle, in which at least a dozen of his victims died.
In the photo, Efron is seen sitting behind the wheel of the infamous ride.
Bundy was convicted of killing and raping several women in the ’70s. He was executed in Florida on Jan. 24, 1989 after confessing to 30 homicides committed across seven states between 1974 and 1978.
Directed by Joe Berlinger, Extremely Wicked, Shockingly Evil does not yet have a release date.