Well it would be hard to screenshot that... and I know your pain. people F1 alot when the are getting pirated just when they are out of reach from scanners. I was bugging a LABC the other day on my Hyena and he got off my scanners and F1ed.
Normally you might be able to screen a befor and after shot and prove that they F1ed and also provide comm chat as well for backup. I have no idea about this one. It would be hard to do a before and after shot.