CBS News is reporting that a Justice Department criminal investigation is trying to figure out just how AIG crumbled. Sources say investigators are digging into whether Joseph Cassano, the former head of London-based AIG Financial Products, and two of his top deputies -- Andrew Forster, an executive vice president, and Thomas Athan, a managing director -- committed securities fraud and other federal crimes.New information has surfaced in the federal investigation of the collapse of insurance giant AIG. As CBS News chief investigative correspondent Armen Keteyian reports, investigators wonder if AIG's downfall was due to criminal acts, such as securities fraud. CBS News is reporting that a Justice Department criminal investigation is trying to figure out just how AIG crumbled. According to Keteyian, sources say investigators are digging into whether Joseph Cassano, the former head of London-based AIG Financial Products, and two of his top deputies -- Andrew Forster, an executive vice president, and Thomas Athan, a managing director -- committed securities fraud and other federal crimes.