by Randy Carey:
Typically, unless some shows up with and presents a death certificate, the customer is assumed to still be alive.
by John Burnett:
There are still a few banks that religiously check the local newspaper for customer obits.
There are also a few in towns small enough that they know about such events (and check them out) before anything formal happens.
And finally, some of them hear from SSA, who was notified by the funeral home, and has now contacted the bank to reclaim a payment or two.