Can a collection agency report on my credit listing without actually owning the debt? What documents must they provide?

I was recently in contact with a collection agency that is trying to collect an alleged debt for $5.00 (yes five dollars!) that occured 6 years ago. I wrote a letter asking them to verify the debt, verify the accuracy of the accounting records, and asked under what authority they have to collect on this debt (do they actually own the debt). In addition, I asked for all supporting documentation. In their response letter, they said that I was past my 30 day verification period; however, they did "verify" the debt. Of course they did not send any supporting documentation supporting their claim. I am not trying to avoid payment. I just want to make sure that I am paying the right amount (was there an account error?) and I want to pay the rightful owner. What documents am I entitled to?