Former New Jersey Governor Jon Corzine -- once the head of mega broker Goldman Sachs -- was to be the savior of the small and struggling brokerage firm MF Global.

He was on the verge of pulling off a sale this week that would have capped his return to Wall Street after losing re-election to Chris Christie.

But that deal has been scuttled, and a federal investigation launched, after hundreds of millions of dollars in investor money went missing. MF Holdings has now declared bankruptcy. Corzine has not been accused of any wrongdoing, but several published reports hint Corzine may have presided over a big Wall Street no-no: mingling customer funds with company funds.

In recent days, MF Global had saw it worth plummet, loosing 67% of it's value and being downgraded to "junk" status. Under Corzine's leadership, MF Global had invested heavily in European debt -- a risky, and costly, gamble.

However, Corzine had maneuvered the company into a position for a sale to a Connecticut company that would have saved it. That deal fell apart amid word the federal regulators were now investigating as much as 900 million dollars of missing investor money.