The fate of hedge fund founder Raj Rajaratnam will be in the hands of a jury on Monday in the biggest Wall Street insider trading trial in decades.

The prosecution closed its case after an eight-week trial in which jurors heard FBI phone taps, three friends-turned-government witnesses and other evidence that Rajaratnam ran a complex web of tipsters between 2003 and March 2009 to make an illicit $63.8 million.

U.S. District Judge Richard Holwell was instructing the Manhattan federal court jury on the law on Monday morning before they start deliberations.

There is so much corroborating evidence ... there is so much independent evidence that it has to be true, prosecutor Jonathan Streeter told jurors on Monday as he finished his closing rebuttal.

Defense lawyers had countered that Rajaratnam, 53, was a successful, aggressive money manager who used a wide array of research, analysis and public information to make his trading decisions.

Rajaratnam's main lawyer, John Dowd, said in his summation to the jury last week: We have shown you times when Raj had taken a position before the recorded conversation. We have shown you other times when Raj didn't trade at all, and when he traded in the opposite direction of what was communicated on the calls.

To convict Rajaratnam, the government's evidence must convince jurors beyond a reasonable doubt that he received material nonpublic information from people who had a duty not to disclose it, and that he knew it was wrong.

The 12 jurors must be unanimous in their verdict. If convicted on charges of conspiracy and securities fraud, Rajaratnam could be sentenced to up to 25 years in prison.

Rajaratnam's October 2009 arrest was part of a sweeping investigation that prosecutors have described as the biggest probe of insider trading at hedge funds on record. Twenty out of 26 people charged pleaded guilty.

Rajaratnam is the only defendant to go to trial so far. A separate trial of four other defendants is scheduled to start on May 16.

The case is USA v Raj Rajaratnam et al, U.S. District Court for the Southern District of New York, No. 09-01184.

(Reporting by Grant McCool; Additional reporting by Jonathan Stempel, editing by Matthew Lewis)