Attys don't understand money and bookkeeping. That's why they are attys.
Gather evidence yourself for now. It's not rocket science and a 'forensic accountant' isn't likely necessary.
Once you have absolute proof take it to an Atty who understands partnership agreements and get some direction. You don't want to end up in court with an idiot judge (hint he too is any Atty and remember attys don't comprehend financials) telling you nothing in your partnership arrangement prohibited the actions.
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