I have no love for Facebook...but...
Why on earth would you even bother reporting it to Facebook. Contact the police. If you saw illegal images on a billboard on the side of a office building would you go in to the building and be happy to be instructed: "Sure, just fill in this form about what you saw and why you think it's illegal and we'll look in to it.." You'd report it to the police. That's what should be done online as well. Screw Facebook and their hopeless systems but let's not elevate them to guardians of law, decency and what is and isn't legal to be posted online.