6 year old compulsive liar is making some strong accusations

So, I'm looking for some advice, please. My girlfriend's 6 year old niece (I'll refer to her as "niece" from here on out) is making some strong allegations against her uncle (I'll refer to him as "uncle" from here on out) regarding an incident on Father's Day of this year.This girl is very open and comfortable with nudity, and is usually naked or close to it at all family functions, as well as often having her hands down her pants. Whatever, she's six, no one makes too big of a deal about it. On Father's Day, my girlfriend's family all got together at her dad's house. At some point, it was just niece and uncle getting some things from a room downstairs from the rest of the house and family.Niece's story is that uncle asked if he could touch her private parts, and then when she said no, asked if she would touch his.Niece told my girlfriend's daughter (I'll call her "M" from here on out) this story while they were being watched by my girlfriend's mother (I'll call her "grandma") last week. Grandma overheard, and told niece's mom (I'll call her "T") what she heard. T then told her sister, Uncle's wife, what niece said. Uncle's wife confronted him, and asked him what happened with Niece on Father's Day.Uncle told his wife that while they were downstairs, Niece had her hands in her pants. He asked her why she had her hands down her pants, and he said "you don't see me with my hands down my pants" and that was the end of it.Obviously, everyone in the family is very concerned and trying to figure out the truth. What is complicating things further is that Niece is a compulsive liar. My girlfriend and I were watching her over the weekend, and on Saturday she told 4 small lies before we even ate breakfast. Nothing big, but she refused to admit to lying about any of them and just kept the lies going. No one in the family knows what to think or who to believe. Uncle has been around all of the kids in the family for 10 years, and there's never been anything like this with any kid until now. We also don't want to completely dismiss Niece, because if she's not lying and we don't listen to her, it will really mess with her mentally and her trust in adults. On the other hand, if she is lying and doesn't admit it, Uncle will be going away for a long time for something that didn't happen, and we're not sure if Niece is quite understanding the gravity of the situation.Although we were trying to figure this out as a family, CPS called T to tell her that they got a report of this all happening, and they were going to open a file and investigate. We're all pretty overwhelmed, and I'm not entirely sure what I'm looking for. Can anyone offer any advice on how to proceed? via /r/Parenting http://ift.tt/2sOCtIc