Jurors completed a first day of deliberations Thursday in the trial of Rajat Gupta, a brilliant Indian-born businessman accused in Wall Street\'s biggest insider trading probe for a generation. The New York federal court jury began with instructions by Judge Jed Rakoff, following three weeks of testimony. The jurors finished their first day without reaching a verdict, although a note was sent out requesting clarification on the charges. Gupta is charged with conspiracy and securities fraud. The 63-year-old faces up to 25 years in prison if found guilty on all charges. Prosecutors say Gupta, who was a board member at Goldman Sachs and headed McKinsey & Co, fed private market-moving information to his former friend and hedge fund manager Raj Rajaratnam, sentenced last year to 11 years in prison for insider trading. The defense says Gupta is innocent and that the government has failed to provide a shred of hard evidence. \"We are now approaching the most important part of this case, your deliberations,\" Rakoff told the jury, before providing instructions on how to consider evidence ranging from wiretapped phone conversations to stock market trades and telephone records. Later, the jury sent a note asking Rakoff to clarify the legal definition of a conspiracy. He wrote back that the term refers to two or more people \"knowingly and willfully\" making an unlawful agreement. An overt act in furtherance of a conspiracy, he said, could be, for example, if \"one of them makes a telephone call to start the fraud going.\" Deliberations were to resume Friday and there was no indication when a verdict in the closely watched case might come.