the act or process of investigating or the condition of being investigated.

a searching inquiry for ascertaining facts; detailed or careful examination.

noun

analysis , case , delving , examination , exploration , fact-finding , gander , hearing , hustle , inquest , inquiry , inquisition , inspection , legwork , observation , observing , pike , probe , probing , quest , quiz , research , review , scrutiny , search , sounding , study , survey , surveying , reconnaissance , catechesis , catechism , disquisition , interrogation , perscrutation