Mind-sifter

The mind-sifter was an interrogation tool used by the Klingon Empire. The device could be used either to scan surface thoughts, or to record and erase all thoughts from a subject's mind. (TOS episode: "Errand of Mercy")

In 2376, a connection between the mind-sifter and the mind controling powers of the ancient Malkus Artifacts was discovered by Klingon Defense Force Lieutenant Toq, leading Lieutenant Commander Data to theorize that the mind-sifter may have been based on Zalkatian technology uncovered on former worlds of the Zalkat Union within the current-day Klingon Empire. (novel: The Brave and the Bold)