What else can my mother do about her identity theft?

So, about two weeks ago my mother gets a call from Best Buy…someone with her name, and social security number opened an account. They were able to do it in the store, and spend money that day. Something must have seemed off, because they called my mother and she denied it…especially since it happened in NC and we live in PA.
She immediately checked her credit, and got fraud alert. Within a day, she got a call…someone at a store was trying to open a credit card in her name, saw the fraud alert and called. They apparently can’t call the cops, but my mother could (it was happening in TN)
Then the next day, it’s happening at Lowe’s, and they spent $7,000 and then called my mother to report the fraud. Nice.

So, she got a credit lock, which apparently means no credit can be given at all and she’ll be getting more calls.
GE Services seems to be failing, as they are allowing people to get the credit and then calling after money is spent.

What else can be done? Will she have to pay any of this back?
(also, how is this possible without her drivers license?!)
We think it must have occurred from my mother seeing many new doctors recently, and possibly someone in an office selling her information. I’ve warned her not to give doctors your ssn.

Is anything spent after the fraud alert was put on going to be cleared from her record? Will they always come after her? She had impeccable credit prior to this, so this is highly upsetting to her.
Any information would be great!