Federal criminal investigators this week charged a former Novato businessman of operating a massive Ponzi scheme, defrauding more than a thousand investors and embezzling tens of millions of dollars to personally enrich himself.The U.S. Securities and Exchange Commission and U.S.Attorney’s Office alleged this week that the late Kenneth Casey and his business associate, Lewis Wallach, were coconspirators who intentionally defrauded 1,300 individuals who invested in their two Novato real estate investments companies, Professional Financial Investors Inc., or PFI, and its associated fund, Professional Investors Security Fund Inc., or PISF.