Go to the local County Seat get applciation for court order that simple, BTW the Judge will ask why, and if he/she thinks you are being paranoid deny the request, however if you can show there is danger to your daughter they would grant it but not to you personaly, probably to a Law Enforcement Agency, FBI usualy.

Have you informed Yahoo?, if not try that. They nearly always act. If criminal have you informed the local Cops?

Whatever happens best wishes

:0)