Want my best guess? Damon must have either refused to answer questions concerning his whereabouts that night, or some other activity, or his trip to Italy, or something, and told police he couldn't tell them because he was a SPY and it was top secret. I know it sounds stupid, but ,hey, look at what we are dealing with.
Oh no, that wouldn't have been a lie to police, would it? LE should have nailed and jailed his sorry butt on the spot for that one.