NEW YORK (Reuters) - Bernard Madoff’s wife, Ruth, is being investigated by U.S. regulators over whether she helped maintain secret records used in the alleged $50 billion (32 billion pounds) Ponzi scheme her husband is accused of running, Bloomberg reported Wednesday, citing a person familiar with the matter.

The U.S. Securities and Exchange Commission found evidence while looking through records at Madoff’s firm that she may have helped track payments, Bloomberg wrote, citing that person.

Bloomberg also reported that the SEC is also looking into why her name appears on related transactions, according to two people with knowledge of the probe.

On Wednesday, a federal judge ordered Bernard Madoff, 70, confined to his Manhattan apartment and told Ruth Madoff to surrender her U.S. passport by noon on Thursday as part of his modified bail conditions. He was arrested Dec 11 and prosecutors charged him with a single count of securities fraud.