There is no "beyond a reasonable doubt" requirement, only a requirement that you decide based on all the information available to you. Since you have access to the police report and other information jibes with it, I think you have every justification to determine that the claimed transactions prior to 8/17 were authorized.
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John S. Burnett
BankersOnline.com
Fighting for Compliance since 1976
Bankers' Threads User #8