I have a 15 year old son who is lying. I know that he is lying so he doesn't get caught for what ever it is he is doing wrong. But how do I make him stop? For example, last night my husband and I were out and when we came home we saw him eating in he family room. Now the rule is no eating in the family room. We also could see him going into the bathroom as soon as he relized that we were home. (We saw the light go on from outside) When we got ion the house my husband called him upstairs and asked him to bring up what he was eating. So he brought up a bag of potato chips. My husband told him to go downstairs and bring up the container he was eating from. (it was empty so he technically wasn't eating from it anymore, that's what my son said) So we went downstairs to see what else was there and there was the lid to the container on the arm of the sofa and an empty drink. My husband went into the bathroom to throw something out and saw a fork in the garbage. So he asked my son how did the fork get into the garbage? My son said "I don't know" So he said you were eating out of the container with your fingers? My son said yes I was. Now I know he put it there, and I said to him that I knew he put it there and that he was only making things worse by lying but he swears up and down that he didn't do it and got mad at me for not beleiving him. So we called our other son and asked him if he put it there and he said no. So now my son says that we always accuse him of the crime right away and never suspect anyone else.  
How can I get my son to own up to what he has done and to stop lying?!