This is only one case that I have personal knowledge of, so I cannot say how widespread this sort of fraud is.
Elderly woman died at home, was buried through a funeral establishment. A relative who had moved into her home many years prior and who was sponging from her wound up running her accounts when the woman declined cognitively.
Following this lady’s death, the relative continued to access her bank account, which was still receiving the SS direct deposit, for some time after her death.
The SS Administration was eventually notified of the fraud, so I would hope that the deposits stopped, but who knows?
There’s a very good chance that the helper lady got a bill for any money the account received after the date of death. Starting from the first of the month that the elderly woman died in. The SS guys get cranky about that.