The government has continued to strengthen its case against Galleon hedge fund founder Raj Rajaratnam (RAHJ rah-juh-RUHT'-nuhm) after one of his former employees pleaded guilty to insider trading charges.

Former Galleon portfolio manager Adam Smith entered the federal plea in Manhattan on Wednesday to conspiracy to commit securities fraud and securities fraud. The charges carry a potential penalty of up to 25 years in prison.

Smith is among more than 15 people who have pleaded guilty in connection with what prosecutors have called the biggest hedge fund insider trading case ever.

Authorities said when they brought the case late in 2009 that those who traded securities based on inside information in the case earned more than $50 million in illegal profits.