Investment fund manager Bernard Madoff pleaded guilty Thursday to the largest fraud in American history and was sent to prison for running a ponzi scheme that defrauded investors out of billions of dollars.

He faces a maximum of 150 years in prison.

Madoff has become a high profile face of criminal greed during the financial crisis - officials alleged that he ran an investment fund that took in new investor's money that was then used to make investment payments to people already in the fund. His investors saw too-good-to-be-true returns on their money.

But because the money wasn't actually invested anywhere and required new investors constantly to pay off the old ones, the scheme eventually collapsed. Madoff's scheme was supposedly worth more than $50 billion-- many people lost all of their life savings.

In this segment, Jeffrey Brown reports on the Madoff guilty plea and talks to two experts about the case.

"I am actually grateful for this opportunity to publicly comment about my crimes, for which I am deeply sorry and ashamed. As the years went by, I realized my risk and this day would inevitably come." - Bernard Madoff

"It's hard to comprehend what $64 billion is. But when you realize that there are probably 100,000 people who've lost their entire life savings because of that one man, it's stunning to look at him and see him standing there." - Helen Chaitman, Madoff victim

"There's a very low chance of recovery in Ponzi schemes. Typically, the money has been used to pay early investors." - Diana Henriques, the New York Times

1. What is fraud?

2. What happens to people who commit fraud?

1. How did this ponzi scheme work? Why did it take so long for it to unravel?

2. Why do you think Madoff did this? Do you think he thought he could get away with it? How do you think he feels now?

3. Does this case make you nervous about investments your parents might make? What should the government do to make sure this doesn't happen again?

4. Do you think is it fair that the judge sent him to jail right away? Why or why not?