Karyn Purvis has lots of free information on line on the web site Empowered to Connect. Check out her comments on lying. I think that she has a reasonable and appropriate response to this issue. Remember that a child who experienced early trauma may have missed key stages of development and not have the ability to quickly change behavior. It is not a matter of finding a consequence that works but rather training him/her as you would a three or four year old. To read more about the Center’s work with trauma click on the link.