Actor Anthony Mackie has joined the cast of The Gangster Squad for director Ruben Fleischer and Warner Bros.

Anthony Mackie will portray former LAPD lieutenant Rocky Washington, although it isn't known how large the role is. The project is based on the true story of an elite LAPD unit trying to keep out East Coast mafia clans from invading the City of Angels. Sean Penn is set to play LA gangster Mickey Cohen, while Josh Brolin, Ryan Gosling, and Michael Peña will play members of The Gangster Squad.

Ruben Fleischer (Zombieland, 30 Minutes or Less) is directing from a screenplay by former LAPD officer Will Beall. The script is adapted from a seven-part series of Los Angeles Times articles written by Paul Lieberman. It isn't known when production will start on The Gangster Squad.

We reported back in April that Anthony Mackie was offered a role in The Gangster Squad, although he was also offered a World War Z role at the same time. It isn't known if Anthony Mackie turned down the World War Z part or not, although it is possible he could take on both roles.