When I was at the call center for my bank we saw it all the time too. I'm sick of our own bank reps suggesting that elderly customers just add their helper as a signer - it strips them of their protection!! -_- I got in trouble once for telling off a banker who had suggested it, haha. Although, it can still be reported as elder abuse they were added in "good faith" but it's much more difficult.
Did you see that a couple states now require us (banks) to report it to this new agency if we see it? I forget all the states, but I know MD was one of them. I wish that was in effect for all states. I just had to do a training even though I don't work in consumer accounts anymore.
Also, the POA doesn't necessarily require an attorney. That's the most common way to have them issued, but you can get those documents online and certified by notaries too. They don't need a "full service" POA necessarily, just one that the bank will accept for that account's purposes.
OP - for the love of all that is good in the world please report this man to SSA and the police. What he is doing is STEALING.
Oh and leave him - but seriously? You have to ask?