Re: In hindsight what changes would you do - Part 1
Organized crime unit of the city vs theatrical bank robber who's killed a few people. Batman had his priorities right at the time since he had no idea just how dangerous Joker would eventually become. The mob didn't even take Joker as a serious threat. "He's not the problem. He's a nobody". Even the amount of money he stole from them was considered peanuts in their eyes.
As for researching Joker, what is there to research? That he likes to steal money and kill his own men? Joker himself was a blank slate with no name, no history linked to his DNA, fingerprints or dental work. Batman had no more to go on than the Cops did when they arrested Joker.
"Sometimes I remember it one way. Sometimes another. If I'm going to have a past, I prefer it to be multiple choice!"
- The Joker