New York  - Convicted swindler Bernard Madoff said he was amazed that his 65-billion-dollar "Ponzi" scheme went undetected for so many years, a lawyer who interviewed the disgraced financier in prison told ABC News.

"He looked pretty good. He seems to be working out. He didn't hold back anything: talked about how he pulled it off, how many years he got away with it. He was very candid with us, very remorseful," said lawyer Joe Cotchett who, with lawyer Nancy Fineman, is suing Madoff on behalf of investors.

Meanwhile, Madoff's wife, Ruth, was sued Wednesday. A court- appointed trustee for her husband's bankrupt investment company said that Ruth Madoff in the last six years had received 45 million dollars, which should be returned to the firm for compensation of fraud victims in the case.

Her attorney denied that Ruth Madoff had any knowledge of the criminal scheme and called the lawsuit unjustified. Most of the couple's assets were already seized last month by federal authorities.

Bernard Madoff was arrested in December and pleaded guilty in March to running a pyramid or "Ponzi" scheme, under which his firm paid huge returns to old investors by collecting money from new ones. The scheme had been going since at least the 1990s.

In June, Madoff was sentenced to 150 years in prison - the judge said that he handed out the longest possible term in keeping with the "unprecedented" fraud Madoff committed. The financier responsible for Wall Street's biggest investment fraud was transferred in July to a federal prison in Butner, North Carolina, and is expected to remain in prison for the rest of his life.

After the four-hour meeting, during which Madoff's lawyer was present, Cotchett said: "Why did he do it? There's a word, and it's a very simple word that we all understand: it's called greed."

Cotchett said he was "dumbfounded" when Madoff said "that he visited with (Securities and Exchange Commission regulators), and there were times when he thought, 'They got me'."

The Madoff scheme was only exposed when last year's meltdown on Wall Street left his firm without the cash to continue paying investors. (dpa)