Conducting an initial client interview with a client who is involved in a custody

You are a paralegal working in a small law firm in Chicago.  You are conducting an initial client interview with a client who is involved in a custody dispute with her partner, and you become fairly certain that the client is lying to you.  What do you think you should do in this stage of the process?  Do you confront the client?  Do you ignore your concerns?  Are there any techniques you might use for eliciting the truth?  Is it your responsibility to elicit the truth?