HI THERE WILL I ALSO HAVE A 10YR WITH ALMOST THE SAME THING SHE WAS SO BAD AT SCHOOL THAT THEY WERE CALLING ME AT WORK EVERY DAY SO I HAD HER EVEALUTED AND THEY SAID SHE HAS ADHD MY DIDNT BELIVE IT NOT MY BABY BUT THIS STARTED IN THE 1STGD AND NOW SHE IN 4THGD AND ITS STILL HARD U HAVE 2 TAKE IT 1 DAY AT A TIME THE LYING AND THE DENIES THINGS U GOING 2 HAVE THAT TALK 2 HER THATS HOW ARE DAYS GO AND GIVE HER LOTS OF TIME ANDLOTS OF LOVE

We've had a great deal of success with this program called Super Pride Cards.  It's an online e-book and it sets up a whole system of rewards and consequences within a larger game with a store and races and points and everything.  Our son just loves it!
You can find it here: superpridecards.com

Okay, I'm concerned as I know you are too.  It's unusual for an 8 year old to say that she had been touched sexually - unless she had been - I don't think that it is common for an 8 year old to understand this or make it up without learning it from somewhere.

You say the police investigated and claim that this isn't true...doesn't mean anything.  

You mention that you talked to her and "she denies it".  What are you referring to?  Does she deny that she was touched or deny that the the police said it wasn't true?  Either way, I'm still concerned, it would not be unusual for a victim to changer their story, especially if they feel that they have reason to be ashamed or they will get into trouble.

Also, you mention that this is the time that her behavior and attitude changed, which also makes me concerned.  

I feel as though you need to have a "heart to heart" talk with your daughter and in an age appropriate way explain to her what is okay and what is not okay and reassure her that you love her no matter what.  Get her to open up to you and find out what is going on.  I would let her know that recently her behavior has become unacceptable and you want to help her, that together you can work this out, regardless of reason.

If you are still concerned that she has been assaulted, find out by whom, and take her to the pediatrician for complete evaluation and the doctor will be able to recommend what you need to do.

I certainly hope that nothing has happened to your daughter and that this will be easily solved with a simple solution.  

Best wishes to you both!

YOU JUST HAVE TO FIND WHAT MAKES HER HAPPY BECAUSE MY DAUGHTER USED TO DO THE SAME THING. I TOOK HER TO SOMEONE SHE WOULDN'T BE SCARED TO TALK TO AND SHE RELEASED ALL HER INNER FEELINGS. I'M SURE YOU WILL BE ALRIGHT. I'M NOT SAYING THAT YOU HAVE TO TAKE YOUR CHILD TO A SPECIALIST BUT HAVE SOMEONE SIT DOWN AND TALK TOHER ABOUT THE INNER FEELINGS SHE HAS.