Bradley Cooper to work on Chris Kyle biopic

'Hangover' star Bradley Cooper has signed on to star in a movie about former Navy SEAL Chris Kyle, who was shot and killed last week by a mentally ill Iraq war veteran. The 38-year-old will also produce the movie. Kyle was killed at a shooting range in Texas, allegedly by Eddie Ray Routh, who is been charged with murder, reported New York Post. Kyle and his close friend Chad Littlefield, who was also killed, brought Routh to the range as a form of therapy to help him cope with a crippling case of post-traumatic stress disorder. It is learnt that Cooper's production company, 22nd 'n' Indiana, bought the rights to Kyle's book, "American Sniper : The Autobiography of the Most Lethal Sniper in US Military History" last year and they will now re-work the script to include his death. Cooper is also said to have recently spoken to veterans at Walter Reed Army Medical Center and discussed mental issues facing returning soldiers.