Father Died, Now There's Fraud On His Cards..

My stepfather passed a few weeks back. He was in his late 70's and neither him nor my mother were the tech savvy types, I am going there tomorrow to handle some things and take her accounts information and create new logins and passwords and keep everything as secure as possible.

Unfortunately the main credit card that they used, which was in his name, but linked to their joint bank account to make payments from has been the victim of fraud. A LOT of fraud in the last few weeks. Basically from the date of his funeral up until Jan 8th when it was finally locked.

The bank said they see this a lot - could be a family member (do have a shady ass step brother everyone is thinking did it) or it could be a compromised account that has been sitting there for a while and when the deceased flag hit, the person went on a rampage but whatever..

Around $50,000 has been charged in the last few weeks. It's a Chase card, but unsure of who the issuer is. Will get that info tomorrow.

My mother tried to dispute and claim it all as fraud as the purchases were made both out of state AND from other parts of our city.

She's very distraught, hasn't had a chance to grieve properly, etc and doesn't know how to handle things so she called the bank and somehow they managed to either get her to agree to (or they just plain did it, not sure) taking $8,000 from the account for payments.

She claims she didn't agree to this and just wanted it locked while they investigate. They was almost all the money she had and her bills are coming due.

I need to figure this out for her. She's almost 80 and this is too much.

What should be my plan of action for addressing this fraud issue with Chase as someone who is not on any accounts and how can I be designated as someone who can do this for my mother, if that's possible?

I cannot go to the physical bank locations with her in person as I'm a school teacher with no time off especially after the holiday breaks and I took days off prior to the break for the funeral already.

Any insight GREATLY appreciated on how to get a hold of this..