'scrutinizer' originates from Latin, specifically the word 'scrutari' (and the related noun 'scrutinium'), where 'scrut-' meant 'to search thoroughly' or 'to ransack.'

'scrutinize' changed from Latin 'scrutari' through Old French/Medieval Latin forms such as 'scrutare'/'scrutinium' and entered English as 'scrutinize' in the early modern period; the agent noun 'scrutinizer' developed from that verb.

Initially, it meant 'to rummage or search through (often rubbish)'; over time it evolved into the more general sense 'to examine or inspect closely,' which is the modern meaning.