There's no way a 9 year-old would say something like that if she wasn't abused. She probably said she was lying, because of her mother or she is afraid of her mother's boyfriend. You definitely did the right thing. I'm so mad at mother's that would not do more to protect their children. I would think if my child at that age would say something like that, I would BEG the police to investigate it and leave that nasty monster of a boyfriend. One day the truth will come and the mother will feel like an idiot and the girl will be mad at her mother for all that.
Maybe you should try to call the police yourself to make sure they're still investigating and don't let it get dropped for any reason. I can understand the way you care about that girl. I've babysat children I care that so much about too. I called the police on my aunt, uncle, and cousin because they were abusing my second cousin. I still question if I did the right thing, because a few people got angry and I'll probably never see my second cousin again. But the main thing is, I tried to help my second cousin. Hopefully, one day he'll have a voice and be able to tell the world about their cruelity and thank me. This is my thread about it:
http://forums.psychcentral.com/showthread.php?t=130188
You did the right thing, don't let anyone tell you otherwise. I hope the police can protect that little girl, since her mother obviously does not. =( I'm glad you took that step to keep her safe. You should call the police and asked them to come to your house, so you can file a report about what she said to you. Anything like that will help her. Keeping having such a big heart. =)
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"Kind words can be short and easy to speak, but their echoes are truly endless." -Mother Teresa
"Respect is love in plain clothes” -Frankie Byrne
“Mankind must remember that peace is not God's gift to his creatures; peace is our gift to each other.” - Elie Wiesel
“Just as despair can come to one only from other human beings, hope, too, can be given to one only by other human beings.” - Elie Wiesel
"And even though you're fed up, Huh, ya got to keep your head up, Keep ya head up, oooo child things are gonna get easier, ooooo child things are gonna get brighter" - Keep Ya Head Up by Tupac Shakur