Right of Redemption on Tax Sale Property

[sospeggy]

I recently bought a property (land only) at a tax sale in Washington. There is a 3 year redemption period only if the owner at the time of the sale was a minor or is found incompetent by the court. I would like to sell this property. I know that the owner wasn't a minor, but have no idea if she was competent or not. I've heard that tax properties are very rarely redeemed, but need to know if I can sell it or not before the 3 year redemption period is up. If so, what kind of deed would I have to use and what do I need to tell the buyer? Also, if it was redeemed, would she just have to pay me what I paid or is there interest involved?