The probe will be led by the FBI's New York field office, which has responsibility for looking into cases involving U.S. citizens in the African region.

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"The encouraging news is that classified operations have, in fact, partially disrupted this threat, " said Mark Mershon, assistant director of the FBI's New York field office.

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The investigation was initiated in the fall by the SEC's New York field office, which estimates investors in the 35 stocks have lost tens of millions of dollars because of the pump-and-dump schemes.

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It must have been a major disappointment to the FBI's New York field office when, in February 2000, Drug Enforcement Administration (DEA) agents arrested Gravano and others in connection with a massive ecstasy ring in Arizona.

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"Certainly we are receiving any information that arrives locally, but any updates or comments would have to come from the U.S. attorney's office in New York, " Stephen Emmett with the FBI Atlanta Field Office told CNN on Sunday.

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