Seems to me you are looking for a lie detector of some sort :lol:
So let me save you some time and tell you that it doesn't exist, unless you want to try sodium pentothal. :wink:
What I can suggest you do is :
1) Read up on behavioural Interview Techniques
2) Make friends with people in other departments so that you can understand the basic principles of how they work
3) Keep in touch with some of the latest business trends
4) Ask candidates the "how did they go about their jobs" and dont focus on the "what did they do" aspect"
5) If you read up on NLP, you will get some very strong indicators of body language. Dont read a book on body language (though there are good ones) because they draw assumptions, which can be mistaken.
A constant practise of ALL of the above will make you a kind of a HUMAN lie detector and a pretty good interviewer.
All the best.
Ryan