Sister is a Compulsive Liar & Thief

Hello,
Not exactly sure where to start.
I have a sister, she is older than I am, and she is a compulsive liar and a thief. She has been lying and stealing for over 10 years now. She started in high school when she started hanging out with a crowd of people who thought that smoking weed and doing heaven knows what else was the cool thing to do. She lost all sense of rules and even of reality.
She's spent the last 10 years stealing SO MUCH from my parents and I. She's stolen thousands upon thousands from me (because I was overly trusting and didn't do a good job of hiding my items for a long time) and heaven knows just how much from my parents. My father even went so far as to put locks on the cabinets in the garage because he does a lot of carpentry and mechanical work, so she stole hundreds / thousands in tools.
The worst part though, for me honestly, is the lying. I've had a hard time forgiving her because over the past two years she has appeared better; however, I've been unable to really forgive her or believe that she was better.
She just got on section 8 and moved out of my parents house after being here for 2 years and having a baby this past winter. She has not been moved out a month, and something has gone missing already.
Now, I am back at home while I attend graduate school and my parents just found out tonight that my father's money that he put in his hiding spot is missing. I was so angry when I found out because my parents are questioning whether or not I might have taken it (because supposedly my sister didn't know about the hiding spot, but I always figured she did) simply to get my parents pissed at her. However, that doesn't make sense, why would I do it after she moved out? She had everything paid for while she was living here, now she's struggling to make it again; therefore, she is stealing.

My mother called her and of course she lied about it. She lies about everything. She lied when she stole my $550 paycheck 2 1/2 years ago that I had put into a money order in order to pay a bill. Mom forced her to fess up (turns out she used it for an abortion,) but it just makes me so mad because she is such an amazing liar that my parents don't know who to believe. Their daughter who has never stolen a thing, has never gotten in trouble with the law, or the daughter who they KNOW has stolen in the past.

I'm so angry with her for having my parents wrapped around her finger. I'm sick of seeing them get hurt. I'm sick of my mother going off to bed crying her eyes out because they're out another couple of hundred dollars and she can't figure out what happened. I do not know how to deal with the situation because she's not my daughter, she's my sister, and all I can do is stand by and watch as my parents allow her to victimize them, and myself. This also explains where my $50 that I put in the same hiding spot a few weeks ago went missing. I figured I was just losing my mind and must have spent it. I guess not.

It's hard dealing with a compulsive liar when you're the only one in the family capable of recognizing the problem for what it is. I'm at a loss.

Thanks for listening. Hope this was okay for my first post. I needed to write somewhere; I'm absolutely heartbroken for my parents right now.

Hey,

I think that, for your sister's sake, you all need to stand up to her with a common front (or consensus) and stick by it. In the future to come, she will just end-up in jail (or worse), but if action is taken then she she might not. Gettign your parents to see the crux of the matter is the issue, as you're implying, so maybe arrange to talk to them both in private about everything that has been going on. As her parents, they are obliged to teach her how to look after herself and to respect others. She seems to be lacking in both respects currently...

Getting her to see that her behaviour is wrong is also an essential point here. You cannot just punish her without her understanding why she has ben punished. Are there any moments where you and her actually talk 'normally'? If so, then those are the moments that are best to begin to talk about the more serious issue (i.e. her stealing and disrespectful behaviour).

Kevin