My 93 year old Dad is being scammed by a woman 25 years younger, who has done it before, but has no police record. Any advice?

So a nearly 70 year old woman is working a scam on your Dad? You say that she "has done it before".
How do you know she has done it before, and what exactly did she do before, and what exactly is she doing now with/to your Dad?
Does your Dad have dementia? Is your Dad handling his own finances still, and is he competent to do so, and to make his own decisions?
The answers to above will help us to give you some hints or opinions on options going forward. Wishing you the best.

Dadswellbeing1, if you could please fill out the profile. That way with more information regarding your Dad, his health, and if he lives on his own, etc. it would help us answer your situation.

How do you know she’s done it before?

And? Unless your father has been deemed incompetent to handle his own life, then he gets to handle his own life the way he sees fit. This is a tale as old as time, where the attractive younger woman finds an older man to sweet talk out of his trousers AND his money. If she has no police record, and he has no dementia, there's not much you can do about it other than try to run her off with threats. Try talking some sense into dad, but don't hold your breath on that.......he is more interested in some pleasure in his old age, most likely, than he is in losing some $$$ at this point.

Good luck.