Santoro joins Carrey in 'Phillip Morris'
The 300 star is the latest cast member to join the film, which is directed by Bad Santa duo Glenn Ficarra and John Requa.
The movie sees Carrey's character, a married father-of-four, fall for fellow inmate Phillip Morris (Ewan McGregor) after being sent to jail. He makes several attempts to escape when the object of his affection is released.
Leslie Mann (Knocked Up) is attached to play Carrey's wife.
It was reported last week that Carrey and McGregor have visited a gay bar together to research their roles.