The Cat Saw Who Did It

I have aided in the capture of a serial killer, which is made even more impressive by the fact that I... am a cat.
Happily settled in with Jane, a would-be victim I helped to save, I thought my days as an amateur sleuth would be traded for belly rubs and sunbeam naps.
Until I watched the man in the apartment complex opposite ours, murder his wife. Once again, it falls to me to help the bumbling humans bring a killer to justice.
Step one is proving to Jane that something horrible happened.
But how do I convince her a crime occurred in the dark of the night? More importantly, how can I prevent her from becoming his next target?