(n.) A scrutinizer; specifically, an examiner of votes, as at an election.

analyst analyzer asker catechist cross-interrogator cross-questioner detective examinant inquirer inquisitionist inquisitor inspector interlocutor interpellator interrogator interrogatrix interviewer investigator observer opinion-sampler poller pollster prober querier querist questioner questionist quizzer sampler scrutineer secret agent tester visitator visitor