Your tax preparer would be a better person to ask this of than attorneys!
Generally speaking, though, you can itemize your losses on Schedule A (but subject to a floor you have to meet; you won't be able to deduct them all).
Also, this is a complicated enough issue that you should have a CPA or enrolled agent (and probably not enough to need a tax attorney).
My inclination is that the casino records should be usable, but keep in mind that they will show additional winnings, too.
I agree with my colleague. This is a question for your CPA or tax preparer. It is not an issue that should require a tax attorney to answer. There are specific limitations that relate to gambling losses and winnings.
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