NEW YORK: Bernard Madoff, who became a symbol of greed in the financial crisis for masterminding Wall Street's biggest investment fraud, faces the rest of his life in prison in one of the stiffest punishments for white-collar crime.

More than six months after Madoff's arrest, US prosecutors remain uncertain how much was involved - such was the complexity of the financial web he wove around the world to operate his Ponzi scheme.

In a Ponzi scheme early investors are paid with money from new clients.