Honesty is one of the most difficult issues for parents. As you have seen, lying can be rewarding in itself when the person who's lying is not caught. The first task in dealing with lying is to find out why the person is lying and then help to correct the underlying reason. The therapist you contact to see your son can help you find out why he is telling lies, and then develop a plan to help stop this behavior.
What's worse: the fact that your son lies, or what he's lying about?
My 11-year-old son lies to get out of trouble. Today a fire got started at my home -- he and his friend were playing with some flammable substance and lighting it on fire. He told me that he didn't know how the fire started, but his friend confessed that they were making a torch with the can of flammable liquid. What can stop the lying, and what kind of punishments will curb this behavior?
Your son's lying is definitely a problem. However, your more immediate problem is that he has begun to set fires and that he is lying to cover up other things he has done. You will want to get some help for your son on this issue as soon as possible. Your son's school counselor or your pediatrician can refer you to a therapist in your area who can work with him.