Chief investigator was a title given to the head of the V'Shar on Vulcan.
In 2154, Stel served as the chief investigator under the V'Las administration. (ENT episodes: "Awakening", "The Forge")
After Stel's removal from office in disgrace, Silok assumed the post under T'Pau's government. (ENT novel: Beneath the Raptor's Wing)