Those people responsible for the 2008 financial crisis yet not charged, they should be charged with breaking what law?

Some form of fraud for misrepresenting the risk that the mortgages that were bundled together, seems like the obvious answer. But I'm not a forensic accountant or someone with the nuanced legal understanding to define a charge here. Do you think there was no crime in the actions taken by either the banks or the rating agencies? No failure of fiduciary responsibility?