Matt Damon, trained killer

In The Bourne Supremacy, Jason Bourne tries to get information out of a CIA employee (Julia Stiles)

This is not obvious from many of his film roles. He played a mathematical genius in Good Will Hunting, a golfer who has lost his swing in The Legend of Bagger Vance and a casino thief in Ocean's 11. Then again, he played a renegade angel in Dogma, and Tom Ripley, a man who kills his friend and assumes his identity, in The Talented Mr. Ripley.

So maybe the evidence has been there all along.

The truth is, Damon--who returns to the big screen as Jason Bourne in The Bourne Supremacy, which opened yesterday--has, in fact, learned the ways of a professional killer. It's a skill set he perfected to strengthen the believability of Bourne, a CIA assassin.

He started with six months of martial arts training and another six months learning boxing for 2002's The Bourne Identity.

'Doug Liman, who directed the first one, decided that the way boxers walked was the way he wanted Bourne to walk. There was a kind of directness in it and an efficiency about the way they moved,' said Damon. 'And it really did work. I felt a huge difference in the way that I moved, it was really interesting.'

Then there was the weapons training. 'Even though I hold a gun in The Bourne Identity for probably a total of 20 seconds, there was a really huge plot point at the beginning of the movie which was that he gets a gun for the first time in his hand and it's like an extension of his arm. And he's so comfortable with it that that's what makes him drop it,' said Damon. In The Bourne Identity, the amnesiac Bourne has no idea he'd been a CIA assassin. 'So the only way to kind of do that is to put in a couple hundred hours of shooting.'