My car was hit by a green car but has white scratch on it. Why?

I have a black Honda accord. Recently someone trying to park in the spot next to me scratched it. She was driving a green van. She is claiming that there was white paint in my car before.

Her insurance company said they are going to investigate. I don't know what to do I think my car had a white primer on it but how can I confirm that. I tried calling Honda but they did not give me any information.

How can I prove that my car was not hit before and the white marks are from her hitting my car.

Did you look for black paint on her van where she could have scraped against your car, most likely a bumper? Paint transfer happens to both vehicles.