He didn't have 40 assaults. He had 40+ arrests,
Yes, meaning he had been quite certainly involved in, like 200 felonies or criminal acts throughout his life. If not more.
Well yes, you don't expect him to have been caught every time he assaulted or robbed someone? Most criminals get caught say, once each 5 crimes. No way they're caught all the times they've committed a bad deed.
So a violent dude with "40+" arrests, has probably behind him a decade or two of regular, weekly crimes. Getting caught when unlucky. And never repenting.
Also, in any normal society, you get arrested more than ten or twenty times by the police, you're not to be seen ever again. Not that I'd necessarily approve, but, that's the way it is in normal places. The cops have seen your face in their patrol car more than 20 times, they gonna drive you somewhere at night, and... Once again, I'm not saying it's a legitimate way of proceeding, I'm just describing how other countries operate.