Neither the grand jury panel nor any individual grand juror may be challenged, but the court may:

(1) At any time before a grand jury is sworn discharge the panel and summon another if it finds that the original panel does not substantially conform to the requirements of chapter 2.36 RCW; or

(2) At any time after a grand juror is drawn, refuse to swear him or her, or discharge him or her after he or she has been sworn, upon a finding that he or she is disqualified from service pursuant to chapter 2.36 RCW, or incapable of performing his or her duties because of bias or prejudice, or guilty of misconduct in the performance of his or her duties such as to impair the proper functioning of the grand jury.