A hedge-fund manager referred to as Tipper X in the Galleon Group insider-trading case could lead prosecutors to widen the probe to hedge funds that had not been previously implicated, the Wall Street Journal said on Wednesday, citing people familiar with the case.

Tipper X was identified as Thomas Hardin, a former trader at Lanexa Global Management, the newspaper said, citing people familiar with the investigation.

The New York Times separately identified the 32-year-old Hardin as Tipper X.

A call to what is believed to be Hardin's home was not immediately returned. Hardin's lawyer could not immediately be located.

Hardin's name is included on a list of potential witnesses that the U.S. Securities and Exchange Commission provided to defense lawyers in the civil Galleon insider-trading case.

A large number of cooperating witnesses could spawn other investigations, the Journal said, citing people close to the situation.

In addition to Hardin, Ian Murray, a New York hedge fund manager who has not been charged with wrongdoing, and Gustavo D'Souza, whose connection to the case is unclear, appear on the list of potential government witnesses, the Times said.

Neither could immediately be reached for comment.

Tipper X was allegedly tipped off to a pending Blackstone Group Inc takeover of Hilton Hotels Corp on July 2, 2007, according to an SEC complaint.

The complaint says Tipper X then passed the information on to Gautham Shankar, a trader who has admitted to trading on inside information.

Twenty-one people have criminally or civilly charged in the Galleon insider trading case that involves employees of some of America's best-known companies.

On Tuesday, a federal judge let stand the $100 million bail set for Galleon founder Raj Rajaratnam, the central figure in the probe.

(Reporting by Bill Berkrot; editing by Carol Bishopric, Dave Zimmerman)