I've asked client for a prepayment and she promised to report me to police.
Hello!
That's a very odd response. Without knowing more about the specific situation, I think she just gave you your first warning sign to take a pass on this project. Stuff like this tells you that you'll likely have a very very very difficult time with this client.
As far as I know, there's nothing wrong. If you seriously still want to work with this client (at your own risk of pain - But don't come and start a new thread here about "I gave the client all the photos, but they refused to pay me, instead they want to report me to police"
), you can try to find out more details about what they are actually objecting to. Is it the lack of any documentation or paperwork? If at this stage you guys can't communicate on basic terms like this, really, do yourself a favour and take a pass. Count yourself lucky that you got away before you put any serious time in.
If you have a proper sales agreement/contract stating the terms and conditions of the deposit, etc., I don't see why any legitimate client would object. Of course, unless they are way bigger than you (gov, MNC, etc), they know you will have to accept their payment terms if you want their business.