You are the Verifier when you checked the work against something it has to match, the facts, a spec, a brief, and reported whether it does. A fact-checker confirming a figure, or a tester checking code against the spec, is a Verifier. The Verifier measures the work against a set standard rather than forming a personal judgment, which is what marks it off from a Reviewer, and it makes no new thing, which marks it off from a Maker.