There should be an anon fund set up where the public can donate ANY level of money with NO LIMITS on amounts. It should be kept PRIVATE and those who donate should be kept SECRET to protect their identity so they do not aquire any backlash. The donors also have NO EXTRA SAY in how the investigation is run.
And who would manage this fund? If "The Bankers" are so entrenched, how will you keep them out?
Who would decide on the investigators? You say "Americans", but you'd be hard-pressed to get them all in a room to vote.