The Spring Breakers actor plays convicted murderer Christian Longo in the forthcoming movie, which details the relationship between New York Times journalist Michael Finkel, played by Jonah Hill, and the killer.

Franco was adamant he would not meet with Longo, who is appealing against the death sentence he received in 2003 for killing his wife and three children, for research purposes.

He tells Yahoo Movies, "This is probably my seventh character that is based on a real person, and sometimes I found that you need to really reference a person and sometimes you go by the script. He's sort of already getting enough attention as it is, and he seems like somebody who might thrive on attention, and I didn't want to give him any more."

After killing his family in 2001, Longo fled to Mexico and used Finkel's name as an alias. After he was apprehended by cops the pair met for a series of interviews and formed an unlikely friendship during Longo's early incarceration.

The movie, which is co-produced by Brad Pitt, hits U.S. screens later this month (Apr15).