[ By Melanie Gretchen ] Before prosecutors actually begin their case against Rajat Gupta on charges he leaked insider information that he learned during his service as a director for Goldman Sachs and for Proctor and Gamble, they have been making the case for the judge to permit 3 wiretap recordings to be entered into evidence.  It's a hotly contested issue, because as Gupta's lawyers point out, their client isn't on any of the calls and, "by the way, was not the source of the information."  The calls feature convicted hedge fund manager Raj Rajaratnam. Prosecutors' Tapes: Circumstantial or Circumspect Evidence. In 1 taped conversation, Rajaratnam is heard boasting to a colleague that a Goldman director had tipped him off about the bank’s coming earnings announcement.  On another, Rajaratnam tells his trader that he’s been told something good is going to happen at Goldman. However... prosecutors do not have recorded conversations of Mr. Gupta leaking this information to the hedge fund manager.  In addition, the lifespan of the 3 wiretap conversations may be limited, in that none of the people actually on the recordings are available to testify during the trial about the contents of the call. Call Records. Nevertheless, prosecutors insist the tapes are essential to their case and should be allowed to be introduced during the case.  Prosecutors plan to use the recordings in conjunction with call records that show Mr. Gupta placed calls to Mr. Rajaratanam around the time of those recordings, and which were made shortly after the end of Goldman board meetings where the relevant inside information was purportedly discussed.  The recordings then indicate how Rajaratnam instructed his staff to execute big trades in Goldman shares. In addition to those recordings, prosecutors say call records show that shortly after the end of Goldman board meetings where other inside information was discussed.  Mr. Gupta placed calls to Rajaratanam - and following those calls, Rajaratnam again instructed his staff to execute big trades in Goldman shares. The case: U.S v. Rajat Gupta for the Southern District of New York. For further details, go to [Dealbook, 5/1/12].