tandum, welcome. sorry about your sister, i agree with cynical, there is nothing you can do to help her. she have to want to help herself. its common for addicts sometimes lie about when and how much they use. i'm a recovering cocaine/crack addict and i can tell you that no matter what you do or say, until she is ready, she will continue down that path.
i think you did what you could by calling the police,now maybe its time to step back and allow her to suffer the consequences of her own actions. focus on taking care of you. read all you can and post as much as you like. check out the stickies at the top of forum page. alanon and naranon meetings are very helpful in learning how to cope with addiction.
i pray that she finds her way soon.