My dad is starting to drive me crazy by 'just asking' how I know Hitler committed suicide, and going on to insinuate that he was allowed to escape by the elite bankers who started WWII. Obviously that's pretty absurd, but it got me wondering: is there anything like DNA or other physical evidence, or if eyewitness accounts and circumstantial evidence is the best we've got?

I'd be especially interested in any books or official reports you could point me toward.