To gain others' trust to confide in you, first tell them a secret to activate the Law of Reciprocation. Then build up to the topic at hand. When doing so, ask about how the person feels about the situation, not about the situation itself. Doing that unconsciously forces him or her to seek support from you.
Detectives do it all the time, but most people don't know how easy it can be to get others to fess up and confide in you. The trick is to follow a series of steps to instill trust and extract honesty. To build trust, tell the other person a secret; this makes him or her feel psychologically closer to you. It also activates the Law of Reciprocation, in which others, feel the need to do for you what you did for them. Next ask a general question about views on a broad topic, and acknowledge the response to build a shelter of trust and understanding. Next, broach the topic of discussion by asking how the person feels about the situation, not about the situation itself. This will open the floodgates to an honest reaction to the situation and allow for further discussion on the topic. Throughout the entire process remember to remain unjudgemental in your words, look, and body language, and if possible, offer a benefit to confiding in you.