Watch The Untouchables Preview on PBS. See more from FRONTLINE.

The PBS Frontline investigation "The Untouchables," airs on Tuesday, January 22, 2013. Frontline investigates how more than four years since the financial crisis, not one senior Wall Street executive has faced criminal prosecution for fraud. Are Wall Street executives “too big to jail"? Check out the preview video above. You can check your local viewing schedule here.