Quote From: bev3horsesI am the oldest of two, just my sister and I, she is 2 years younger than me. Ever since I can remember my sister has been a compulsive liar and a minor thief. After 10 or so years of lying and thieving, it finally landed her in jail, but only for a short time. I've never met anyone like her, she will lie about what she ate that day, where she went, who she talked to, how much money she has, what her children did that day, why she is late (because she's always late). Do you know how many times she's been pulled over by the cops, or was caught behind a traffic accident? Probably never but it seems she has that problem everyday and we do not live in a big city where things like that happen everyday. 
You just can't believe a word this girl says, she's cried wolf so many times. I honestly believe that she believes her own lies, she tells them so often and to so many people that she almost has to believe them to keep the story straight. And, she is very good at keeping her story straight, most liars mess up somewhere, but not her.  
She actually lied about graduating high school, she made her own copy of a diploma, and her resume is laughable, college graduate with honors and all of the bells and whistles, which aren't true. 
When she finally did get arrested for forging some checks, she lied to her husband and our entire family so that we would feel sorry for her and think she actually hadn't done anything wrong. We found out about a month later, while she was in jail, that she had actually committed the crimes that she was charged with. We found out not from her but from some legal paperwork etc.. My family was devastated to find out that we had all tried to help her and stick by her and for what?? a LIE!!  
It's very hard having a close family member that you can't trust. I worked with her a few years back at a job where cash and checks were handled, before I knew she had sticky fingers, and I almost was arrested because of her. She finally told the police I had nothing to do with her theft, nor did I know anything about it. Boy was I FURIOUS that time!! I have been a hard working honest person my entire life and I surely wasn't going to be arrested for something I had nothing to do with. Thank God that all worked out. 
I don't know that I will ever be able to believe her now, everything she says you have to second guess and verify before you take it as truth, it's not easy living that way, but we do it because we honestly do love her even if we hate the things she does. 
She did see a psychiatrist regarding her complusive lying and they agreed she actually does have an addiction to lying, she's working through that with weekly sessions now that she is home. I hope that eventually with maturity will come realization of her mistakes. 
Thanks for listening/reading my rant. 
BEV3HORSES 
I sure hope your sister gets help ASAP. It is VERY DIFFICULT to live with a person with this kind of a problem/addiction. You're right, it gets to the point that you can't trust ANYTHING they say - and I don't anymore. I wouldn't believe him if he said it was 10 degrees outside and it really was! My brother is 54 years old now and his lying continues. I'm just fortunate to not live in the same state as he does, so don't have contact with him on a regular basis anymore.
Your sister's story sounds a lot like his...the stealing, jail time, sticky fingers, forging checks...I think you're right...it gets to the point that they actually believe their own lies. He seems to keep his stories straight too. I just wish my brother would get some help. I don't think he will ever have a long-term relationship with a woman until he does.