Us the Reviewers filter to locate all documents for which that reviewer was the last to apply work product. Reviewers who have accessed the database but have not Marked any documents will show up under Reviewers in the Filter Tree with no number after the name:
(In the example above Alison has Marked one document. Cwaterman and Paulette have not Marked any documents.)
NOTE: You must have the Reviewer column currently in the Document List in order to search by Reviewers. See Edit Columns