A device of Tok'ra construction, specifically designed to determine whether or not a subject is a za'tarc -- a subconsciouslly programmed Goa'uld assassin. An arm built onto the device analyzes the retina of a subject, and in conjunction with the Tok'ra memory device, compares the conscious memory to the unconscious mind. If they do not match, it is concluded that the subject has been programmed to be a za'tarc and the event covered up with a false memory.
The za'tarc detector is not entirely reliable, having given false positives on at least three occasions. The device is also used as a lie detector, since the subconcious mind cannot be made to believe a lie.
Divide and Conquer - The Tok'ra Anise arrives to test all S.G.C. personnel, to see if they've been affected by Goa'uld mind control.
Absolute Power - The Tok'ra Aldwin brings a za'tarc detector to Earth to test Shifu, the Harcesis child of Sha're and Apophis.
Allegiance - A za'tarc detector is used to determine whether or not a Tok'ra or rebel Jaffa is behind a series of mysterious murders at Earth's Alpha Site.