1 Samuel 28:9

And the woman said unto him, since she suspected that this was a test, a trap to catch her and convict her, Behold, thou knowest what Saul hath done, how he hath cut off those that have familiar spirits, the order for their extirpation having been carried out with great rigor, and the wizards, out of the land; wherefore, then, layest thou a snare for my life to cause me to die? Cf Leviticus 20:27. Evidently this was the manner in which necromancers were caught, when they agreed to a request as here made by Saul.