From extra weight to a funny toupe, Vin Diesel went to extremes for his new role

As an actor best known for battling alien races, driving fast cars and hobnobbing with a duck, "Find Me Guilty" presented myriad challenges for Vin Diesel.

"I don't know if it was the collective Team Vin, but yes, there were those concerned voices that were saying, 'Are you sure you want to do this? You just turned down all this money for this one picture and you're doing this movie and you're not getting paid and you're creating a character and a look that won't comply with all the other action films,'" Diesel says of his latest film.

In "Find Me Guilty," Diesel plays Jackie DiNorscio, a real-life New Jersey mobster who refused to testify against his friends, representing himself in one of the longest trials in United States criminal history. The film, directed by Sidney Lumet, is a difficult-to-describe blend of legal drama and gangster comedy, miles from high concept vehicles like "The Fast and the Furious" or "XXX."

"I'm so used to being a superhero every day," Diesel laughs. "I loved the fact that I was able to gain weight. I loved the fact that I was able to perform within the confines of the character. I loved that there were no special effects and there was no sex scene, there was nothing obvious."

Diesel was drawn to the project by the opportunity to work with Lumet, a legendary actor's director with a resume ranging from "The Pawnbroker" to "Serpico" to "Network."

"Most of the directors that you'll come across nowadays will divide their attention amongst the CGI, the special effects, the set, all of the other elements and find that actor-director relationship amongst all of that," Diesel notes. "Sidney Lumet starts with the actor-director relationship. ... He wants you to deliver your best performance and goes to great lengths to create an environment for you to realize that dream of becoming a character."

At times, Diesel is nearly unrecognizable as DiNorscio. In addition to donning a goofy hairpiece, he adopted a new voice and posture, eschewing his buff exterior for a hard-earned layer of flab.

"It made me very anxious in the beginning, because now there was this person that I was being compared to and my character would eventually have to match up in some way to the real Jackie DiNorscio," explains Diesel, who shed all traces of the character's extra weight after shooting. "I spent a long time building the character, amassing the attributes and characteristics and mannerisms and physicalities of the character and then I had the great fortune of meeting Jackie DiNorscio."

The real Jackie D. died during the production on "Guilty" and Diesel still seems devoted to his memory.

"He was a comedian, even when he needed five guys to lift his wheelchair to get him into the trailer," he recalls. "He was joking till the last minute... That was what was special about Jackie, that he could find the humor in any situation."

"Find Me Guilty" opens on Friday, March 17.