If the individual taking over control of the account is the executor, administrator or other personal representative of the estate of the deceased account holder, my opinion is that he or she could inquire into the nature of the transactions and challenge as unauthorized any that were initiated after the owner's death. In practice, transactions that would have to be paid from the estate anyway (as Andy mentioned) wouldn't get challenged.
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John S. Burnett
BankersOnline.com
Fighting for Compliance since 1976
Bankers' Threads User #8