Paying taxes on Unclaimed Funds

Hello, my friend did not receive royalties for several books and the publisher flung the money into Colorado Unclaimed Funds. I managed the get the money (exceeding $5000) and it looks like they took taxes out. I don't think I can get a tax form from Colorado Treasury any time soon. Do I file for this? What form should our accountant use? I'm afraid this will be a mystery to my accountant so I'm asking here to get information. Thank you!

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