It's pretty simple

“A child of five could understand this. Send someone to fetch a child of five.”
― Groucho Marx 

Ever notice how the shortest and simplest questions can be the hardest to answer? 

"What did you know and when did you know it?"

"Where were you and who were you with?"

"What did you do and what happened then?"

"Who did you talk to and what did they say?"

"What does it do and why is it important?"

"Who said it and what did they mean?"

Whether you're quizzing your kids, conducting an interview, performing an inquisition, or just trying to understand something or someone better, asking a simple question and then shutting up and listening has proven to be the best technique.

If the person doing the answering has all the facts and isn't trying to hide something then the answers are as simple as the questions.  However, if the answers are being fabricated and/or distorted then the answers have more adventure.

Professional interrogators are trained to ask questions three times.  If the answers each time are as clear and succinct the third time as they were the first then it's probably an honest and accurate answer.  If each answer changes or if from the beginning the answer rambles, dips, weaves and essentially doesn't make sense then either the facts or the truth is in question.

So, when you're the interviewer keep your questions clear and simple (and remember the shut up and listen part).  If you're the interviewee have your facts straight and your story accurate.  If you don't know the answer it's probably better to fess up and admit you don't know and if you're trying to hide something, well, that's a horse of a different color.