13. Evidence for prosecution and examination of witnesses-Re-examination by prosecutor. -The oral and documentary evidence for the prosecution shall then be exhibited; the witnesses shall be examined by or on behalf of the prosecutor and may be cross-examined by or on behalf of the person accused. The prosecutor shall be entitled to re-examine the witnesses on any points on which they have been cross-examined, but not on any new matter, without leave of the commissioners, who also may put such questions as they think fit. | 