On what basis can a prosecutor in a sexual assault case rely on perjurious or hearsay testimony before a grand jury?

On the other hand, the prosecutor's right to exercise some discretion and selectivity in the presentation of evidence to a grand jury does not entitle him to mislead it or to engage in fundamentally unfair tactics before it. The prosecutor, for instance, may not obtain an indictment on the basis of evidence known to him to be perjurious, United States v. Basurto,497 F.2d 781, 785-86 (9th Cir. 1974), or by leading it to believe that it has received eyewitness rather than hearsay testimony, United States v. Estepa, 471 F.2d 1132, 1136-37 (2d Cir. 1972). We would add that where a prosecutor is aware of any substantial evidence negating guilt he should, in the interest of justice, make it known to the grand jury, at least where it might reasonably be expected to lead the jury not to indict. See ABA Project on Standards for Criminal Justice The Prosecution Function, 3.6, pp. 90-91.