There is something missing from your question. Forget that the accounts were for you, who's name was listed as the owner? Im assuming the decedent because you dont have a Trust own POD/TOD accounts. If true, how did the Trustee access those accounts? Did the trust have Power of Attorney? If so, were the funds necessary for the decedent's use.
I think your instinct are right. Its just a matter of what violation. You need to hire a trust litigation attorney.
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Mr. Schultz put his finger on the immediate issue - if the POD account(s) were owned by the decedent how were they accessed as POD doesn't "kick in" until death. I assume they were mishandled under a POA - is the trustee the same person as the POA? You have options but it is likely a question of whether it is abuse of the POA on those accounts or a trust issue.
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The real question is more along the lines of whether the Trustee violated any fiduciary duties, either to the decedent, or the beneficiaries. If the trustee appropriated trust funds -- or funds that should have been in the trust, there is certainly a problem.
The information above should not be considered legal advice and does not create an attorney-client relationship.