Horrible people. Really sorry to hear about your mates daughter, hope shes doing ok now, hope she can carry on and move forward in her life.
I'd get that fucker and any of his mates as well personally, somethings you just have to take into your own hands in my opinion.
And I agree with The Individual, they will get a couple or a few years in prison and then be out and probably doing the same thing again, theres no justice in the courts.