The criminal investigation into who knew about money manager Bernard Madoff's massive fraud has expanded to include some of his highest-profile investors, the

Wall Street Journal

reports, citing people familiar with the matter.

Philanthropists Jeffry Picower and Stanley Chais, who invested heavily with Madoff, and Carl Shapiro, one of Madoff's oldest friends, are among at least eight Madoff investors and associates being investigated by the U.S. attorney's office in Manhattan, the

Journal

reports.

Federal investigators have gathered evidence they think will show that Picower and Chais told Madoff how much in returns they wanted, and their accounts soon would reflect those amounts, people familiar with the investigation said, the newspaper reports.

Madoff family members and employees continue to be investigated, but the probe now includes investors who have claimed to be among the hardest-hit victims of the fraud, both directly and through their foundations, the

Journal

notes.

Madoff pleaded guilty in March and is set to be sentenced next month.

A lawyer for Picower, 67 years old, said his client wasn't complicit in the fraud and suffered losses in the billions, according to the

Journal

. A lawyer for Chais, an 82-year-old money manager who channeled West Coast clients to Madoff's firm, said he was unaware of a criminal probe of Chais and his client didn't have knowledge of Madoff's Ponzi scheme, while a representative for Shapiro, 96, said Shapiro had no knowledge of the fraud.