Why Are Mug Shots Always So... Off?

I keep noticing that the mug shots posted from time to time in the local papers are always somehow just "off."

This is a mug shot of a guy named Charles Willis and the police in Milford, Delaware, are looking for him. I know nothing about this guy, but his mug shot matches the off-centered-ness of many I've seen in the local press lately.

Why can't these mug shots be better centered? It's off-putting to see them this way.