That scheme called for FBI "clean teams" to interrogate the tortured person after the torture was completed, using conventional and lawful interrogation techniques. These techniques often proved more successful than CIA torture. Because these techniques were lawful, and the person being interrogated was advised of his rights and treated humanely by the FBI, the information thus obtained from him was usable in federal court.
Pretty much the most extreme form of "good cop, bad cop." Just tell the tortured victim that unless you tell the "
clean teams" from the FIB what we want them to hear you'll get the electrodes back on your nutsack.