A former attorney has pleaded guilty to securities fraud in a massive insider trading case already brought against one of America’s richest men.

Brien Santarlas entered the federal plea Thursday in Manhattan. He is cooperating.

The Hoboken, N.J., resident said he gleaned inside information from law firm computers about pending acquisitions and mergers. He said he also eavesdropped on secret conversations and asked unwitting colleagues questions about deals.

Billionnaire Raj Rajaratnam (RAHJ rah-juh-RUHT’-nuhm) has pleaded not guilty in case. Authorities say ill-gotten gains totaled $53 million.

Santarlas could face up to 25 years in prison when he’s sentenced next June.