"Counter-espionage: interrogation". Mikhail Kryzhanovsky, KGB

Interrogation is a conversational process of information gathering. The intent of interrogation is to control an individual so that he will either willingly supply the requested information or, if someone is an unwilling participant in the process, to make the person submit to the demands for information.
   Remember, people tend to:
-talk when they are under stress and respond to kindness and understanding.
-show deference when confronted by superior authority, This is culturally dependent, but in most areas of the world people are used to responding to questions from a variety of government and quasi-government officials.
-operate within a framework of personal and culturally derived values. People tend to respond positively to individuals who display the same value system and negatively when their core values are challenged.
-respond to physical and, more importantly, emotional self-interest.
-fail to apply or remember lessons they may have been taught regarding security if confronted with a disorganized or strange situation
-be more willing to discuss a topic about which the interrogator demonstrates identical or related experience or knowledge
-appreciate flattery and exoneration from guilt

 Procedure

  Before you interrogate the object, you have to gather some intelligence on him — examine his documents, read his files (if any), interrogate his partners or co-workers. Then you must establish and develop rapport, when the object reacts to your statements. Rapport may be developed by asking background questions about his family, friends, likes, dislikes; by offering incentives like coffee, alcohol, cigarettes, meals, or offers to send a letter home; by feigning experiences similar to those of the object; by showing concern for the object through the use of voice vitality and body language; by helping the source rationalize his guilt; by flattering the object. Be convincing and sincere, and you’ll control the object for sure. ( Hollywood “insists” on using the “truth serum”, but I can tell you one thing – KGB never used it, a professional interrogater does not need it. I know about tests with Oxytocin, when 130 college students were randomly given a snort of  Oxytocin or placebo. Half   were then designated “investors” and were given money. They could keep or transfer some or  all of the money to a student “trustee”, whom they did not know and could not see. The act of transferring money tripled its value, creating a big payoff for the trustee receiving it. That person could then keep it all or acknowledge the investor’s trust by  returning some portion.  The investors getting Oxytocin on average transferred more money than those getting placebos, and twice as many – 45% versus 21% - showed maximal trust and transferred it all. Oxytocin had no effect on how much money trustees shared back with their investors, suggesting that the hormone acted specifically to promote trust in situations where there was risk and uncertainty.  My conclusion is : you can you drugs like Oxytocin to improve and accelerate rapport, nothing else).
 After that you can start questioning using follow-up questions (they flow one from another based on the answer to previous questions), break-up questions (to “break” the object’s concentration, if he’s lying, by interrupting him all the time), repeated questions (to check the previous information), control questions (developed from information you believe to be true and based on information which has been recently confirmed and which is not likely to be changed. They are used to check the truthfulness of the object’s responses and should be mixed in with other questions throughout the interrogation), prepared questions developed in advance of interrogation to gain precise wording or the most desirable questioning sequence (they are used primarily for interrogations which are technical in nature), leading questions (to prompt the object to answer with the response he believes you wish to hear) to verify information. 
 There are two types of questions that you should not use - these are compound and negative questions. Compound questions are questions which ask for at least two different pieces of information and they are, actually, two or more questions in one. They allow the object to avoid giving a complete answer. Negative questions are questions which are constructed with “no,” “not,” “none.” They should be avoided because they may confuse the object and produce false information.
 Never allow the suspect to deny guilt. But it’s good if he is involved in discussion and gives you the reason why he didn’t or couldn’t commit the crime, because you can prove he’s wrong and move him towards  offering alternatives  and giving two choices for what happened; one more socially acceptable than other. The suspect is expected to choose the easier option but whichever alternative he chooses, guilt is admitted. Also, offer punishment alternatives and deals and lead the suspect to repeat the admission of guilt in front of witnesses.
Tricks:
a) “good cop / bad cop”
b)“story under a story” (after intense interrogation the object tells a different story — which is not true, either)
c) “bombing” with questions
d) pressure by not interrogating
e) “silence makes your situation worse” trick
f) “admit one small episode and that’s it” trick
g) “I help you — you help me” trick
h)   “shift”  - try to shift the blame away from the suspect to some other person or set of circumstances that  prompted the subject to commit the crime. That is, develop themes  containing reasons that will justify or excuse the crime. Themes may be developed or changed to find one to which the accused is most responsive.
 Remember, every object has a breaking point and there are some indicators that the object is near his breaking point or has already reached it. If the object leans forward and his facial expression indicates an interest in the proposal or is more hesitant in his argument, he is probably nearing the breaking point.

  If you are being interrogated,

your major objective is to buy time and use “effective talking,” disclosing information that is correct, but outdated or worthless.   I can add also a few words about  the polygraph (“lie detector”) , which measures heart rate, blood pressure, respiration rate, and skin conductivity to detect emotional arousal, which in turn supposedly reflects lying versus truthfulness. The  polygraph does in fact measure sympathetic nervous system arousal, but scientific research shows that lying is only loosely related to anxiety and guilt. Some people become nervous when telling the truth, whereas others remain calm when deliberately lying. Actually, a polygraph cannot tell which emotion is being felt (nervousness, excitement, sexual arousal) or whether a response is due to emotional arousasl or something else, such as physical exercise. Although proponents contend that polygraph tests are 90% or more accurate, tests show error rates ranging between 25 and 75 percent.  My own experience  says that you can successfully  lie to  polygraph. In 1987, while at  KGB Andropov Intelligence Institute, I was tested by “lie detector”, and I failed the first set of questions, like :” Have you ever cheated on your wife?” or  “Do you like prostitutes?”. Then I relaxed for half an hour watching  other students going through the procedure, and took the test again – this time I tried to stay absolutely indifferent  and “programmed” to lie. I won . I think, the best thing  is to use “guilty knowledge” questions to make the polygraph reliable – that is, questions based on specific information that only a guilty person would know ( such as the place where the object (a “mole”) had a “brush contact” with intelligence officer) – the idea is that guilty person would recognize these specific cues and respond in a different way than an innocent person.