inquisitorial

Having the authority to conduct official investigations.

“the inquisitorial power of the Senate”

Marked by inquisitive interest; especially suggestive of an ecclesiastical inquisitor.

“the press was inquisitorial to the point of antagonism”

“a practical police force with true inquisitorial talents”

Especially indicating a form of prosecution in which proceedings are secret and the accused is questioned by a prosecutor who acts also as the judge.