I have had custody of my daughter for most of her life. I now know why I have been audited. The mother(we were never married) has been taking all deductions concerning child care, and even claimed her as her dependent on tax return. Should I file some amended returns, turn the mother in for fraud or try to get an advocate to fill me in on the laws and what to do?

There is nothing you do except provide them with the evidence that you are the one legally to take the deductions, also showing the court order giving you full custody of the child.

If they decide to follow up on IRS violatons that is up to the IRS.

Fr Chuck has it right. Present YOUR side of the case and let the IRS decide.