A guy is harassing me and threatening my friend.. What should I do?

[Naveen]

There is this girl. She is really really scared and also kinda stupid.
A guy claims to love her on facebook and harasses her and threatens her using strong offensive language while being drunk. He got to know about this girl through some common friends and now all those people have drifted apart.. leaving this guy harassing this friend of mine.
He has downloaded some of her pictures from facebook, is making fake profiles and sending friend requests to the girl's friends and talking in a degrading language and deafamising the girl. Also he wants the girl to recognise him as his boyfriend and marry him.. He claims to be an IPS officer too.. The girl is scared and has become quite emotionally disturbed. She also is afraid that her parents may find about this and she might get in trouble.
Is there any way that she can anonymously lodge a complaint against this guy and stop these threats ?
Also she is not even sure that the guy had given her his real name and she doesnt really have any viable information about this guys.. What are the options she has ?? And what steps can she effectively take..
Also She lives in kolkata and the guy claims to be from Patna.. They have never met personally. The photographs the guys possesses are of the girl which he merely downloaded from facebook, The do not appear together in these pictures nor are these pictures in any way discriminating to the girl..
Please help..
Thanks in kind appreciation and anticipation.

[Sentif Youshien]

No one is harassing you imagining things there is no such thing as the F.B.I. or C.I.A and no one is following you you need to clean your room it smells and you dont know.

[lolly]

So the Facebook you use has no Block or Report User feature? Ok then.

https://www.facebook.com/help/290450221052800
https://www.facebook.com/help/181495968648557/

[Alex Mercer]

F-ck off sentif, you are a shame to this community. What the hell will you do if your daughter is bullied like that? You are one ignorant dipsh!t.

What can you do?

1. http://goo.gl/8ZAhMf
2. There is a feature called 'block' in facebook.
3. Announce and tell your friends as soon as you can.
4. Those people who disturb others on the net are just cowards living in their small room. Total rats. Just call the cops as an anonymous. Never believe what he says.
5. Ignore him!
6. Take immediate action- don't delay, Tell the school admins or someone who is an adult and knows what to do.
7. Have a safe password!
8. If you want an adventure, piss him off! Make fun of him! Gather your friends and you know, bully him... Let her in that group and f-ck up his whole timeline. And cheer that girl up- she might even commit suicide! If your friends refuse to make a group to piss him off, or even for cheering her up.... destroy every accounts and evidences/traces online, before it gets too late.

Good Luck!