My friend committed suicide?

[Been There]

The CIA does not get involved in bullying.
The Courts only take cases that the police have forwarded to them for trial.
So go to the local police.
You could also go to Student Services at your university, since Tierra and Melissa are also students there, and report what has happened. Perhaps the school might end up kicking them out.

Bullies will not be jailed for life. Fined perhaps, but not jailed. This hardly matches the damage they have done.

It is tragic what happened.
But Christina always had the option to stop going onto Facebook, and her decision to kill herself was her decision.
Yes, bullying MUST be stopped.
But the bullies did not control Christina. The problem is that Christina did not control Christina either.

I am truly sorry for the loss of your friend.
I am truly sorry for Christina's unhappiness that led to her taking her life.
Don't YOU let yourself be this unhappy.
Especially do NOT feed you anger and revenge . .this will screw you up big-time. Get some counselling for your grief, so you can figure out how to process and get over this experience. And not end up permanently wounded. We just are not raised or taught how to do this, so don't feel guilt for getting counseling.. And certainly, Christina did not get the help she so desperately needed. See if Student Services at your university can give you some grief counselling, or direct you to where you can find some.
Best to you.
Take care of yourself, dear one.