Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
vestīgātor or vestīgĭātor, ōris, m. [vestigo], a tracker, spy, tracer, searcher (not in Cic.): vestigator a vestigiis ferarum, quas indagatur, Varr. L. L. 5, § 94 Müll. (where the read. is vestigiator); so Col. 9, 8, 10; Sen. Ben. 3, 26, 2; Dig. 33, 7, 12, § 12.