FBI investigating, will that help?
Unless the universe has just repealed the laws of economics and laws of markets, there are only too possible culprits (since free markets are by nature self correcting). That leaves first Congress, who has distorted the financial market through backing corrupt endeavors like Fannie and Freddie, throwing a wrench into lending due diligence to low income families and passing laws like Sarbannes Oaxley.
Secondly, much of this crash must trace to loose Fed policy, which caused the crash of the dollar, inflation of commodities ranging from Gold to oil to corn, and flooded the subprime lending market with free money.
This really isn't hard folks, no matter what the bureaucrats tell you.