A former Atheros Communications Inc executive pleaded guilty on Wednesday to conspiracy and fraud charges in the Galleon hedge fund insider trading case.

Ali Hariri, a former vice president of the Santa Clara, California, chip-maker, is the 10th person to plead guilty out of 21 traders, lawyers and executives accused last October and November in a probe that ensnared prominent Galleon founder Raj Rajaratnam.

U.S. prosecutors described the probe as the biggest hedge fund insider trading case ever in the United States. Much of their evidence was gathered using wiretaps and cooperators.

Eight people, some of them Rajaratnam's former friends and business associates or onetime Galleon employees, have signed cooperation agreements with federal prosecutors and may be called upon to testify at criminal trials.

Ali is a good man who made a mistake and he is going to pay a high price for it, Hariri's lawyer, Cristina Arguedas, told reporters after the plea proceeding in Manhattan federal court.

Hariri, who is free on bail, told a magistrate judge that he provided a friend with confidential financial information about Atheros. When Hariri was arrested in San Francisco last Nov. 5, prosecutors said that between 2008 and March 2009 he provided inside information to a cooperating witness who managed a hedge fund in California in exchange for advice about trading in other stocks.

The cooperating witness was later identified as Ali Far, a founder of Spherix Capital LLC and a former Galleon employee.

Hariri's sentencing was scheduled for June 10, when he faces a prison term of between 24 and 30 months under federal guidelines. The plea did not include an agreement to cooperate with the government, his lawyer said.

Two of the principal defendants, Rajaratnam and former New Castle Funds LLC employee Danielle Chiesi, have pleaded not guilty to criminal charges and vowed to go to trial, which is scheduled for Oct. 25.

All of the accused also face civil charges by the U.S. Securities and Exchange Commission over allegations they made tens of millions of dollars in illegal profits by trading on confidential tips ahead of mergers and acquisitions from around 2003 to last year.

The arrests and charges drew widespread attention because they included allegations against a well-known hedge fund figure in Sri Lankan-born Rajaratnam and employees of some of America's best-known companies, including International Business Machines Corp , McKinsey & Co management consultants and Intel Capital, investment arm of Intel Corp .

The cases are USA v Ali Hariri, U.S. District Court for the Southern District of New York, No. 09-mj-02436; USA v Raj Rajaratnam and Danielle Chiesi, No. 09-01184 amd USA v Zvi Goffer et al No. 10-00056. (Reporting by Grant McCool; Editing by Tim Dobbyn and Matthew Lewis)