On why Republicans and Democrats are not pursuing elite white collar crime: It would hurt campaign contributions. Finance is the leading source of campaign contributions for both parties.
On how to "hotspot" white collar crime: Going after issuers of "liars' loans" would have been the obvious way to go. You always have insufficient resources so you always look for choke-points. There are only 3 credit rating agencies, for example. If you investigated even one of them for the frauds they were committing - giving AAA ratings to liars' loans - you would have shut down the entire secondary market and the fraudulent loans. There are also only 5 investment banks. If you had gone after one of them... Lehman Brothers, for example. Or Aurora - where they fired the fraud guy because he made a criminal referral. With very few resources you could have prevented the entire crisis.
On how hotspotting would have stopped the fraud: Hotspotting puts a shot across the bow of the rest of the industry. You have to have the regulatory cops on the beat... and they took the cops off the beat.