The chief executive of expert networking firm Primary Global Research LLC has been implicated in the government's sprawling insider trading probe, court papers show.

Unni Narayanan, the chief executive, has not been charged with wrongdoing, but is one of the highest-ranking executives linked to the investigation announced in October 2009 and which has led to guilty pleas or convictions for nearly all the roughly 50 people criminally charged.

Narayanan is among six onetime Primary Global employees who, prosecutors believe, participated in a scheme to defraud certain public companies of material, nonpublic information, according to a filing on Tuesday by Ethan Balogh, a lawyer for former Primary Global sales manager James Fleishman.

Balogh said the government identified Narayanan and the other colleagues in a confidential July 15 court filing related to its case against Fleishman, who faces an August 29 trial in Manhattan on two conspiracy charges.

Among the others named is Phani Saripella, a former chief operating officer at Primary Global, which is based in Mountain View, California.

Dan Charnas, a spokesman for Primary Global, declined to comment. The U.S. attorney's office in Manhattan had no immediate comment. Efforts to reach Narayanan and Saripella were unsuccessful.

INNOCENT, LAWYER SAYS

At least 14 people have been charged in the part of the insider trading probe focused on expert networking firms, which use consultants to match industry experts with money managers.

Twelve, including former Primary Global employees Don Ching Trang Chu and Bob Nguyen, pleaded guilty. Winifred Jiau, once a Primary Global consultant, was convicted at trial on June 20.

Mr. Fleishman is innocent, Balogh said in an interview on Tuesday.

Others affiliated with Primary Global and identified in the filing as having participated in the scheme include Nguyen; Bayard Fleitas, a vice president in sales; and Rajan Varadarajan, head of advisory services.

The filing also names one dozen consultants and clients said to have been involved. At least six have entered guilty pleas, including hedge fund manager Samir Barai.

Fleishman faces charges of conspiracy to commit securities fraud and conspiracy to commit wire fraud. His trial before U.S. District Judge Jed Rakoff is expected to last roughly three weeks. Rakoff also presided at Jiau's trial.

The best-known defendant in the insider trading probe, Galleon Group hedge fund founder Raj Rajaratnam, was convicted at trial in May.

The case is U.S. v. Fleishman, U.S. District Court, Southern District of New York, No. 11-cr-00032.

(Reporting by Jonathan Stempel; editing by Gerald E. McCormick and Andre Grenon)