Someone opening account etc

Question

my sister has never been on facebook and according to people she has been given abuse to people via facebook she doesnt even have access to a computer it is causing alot of problems and the police are involved i am deeply concerned for my sister as she is being threatned not on facebook but as a result of things that are being said on here i am worried as my sister is heavily pregnant. i would much appraciate it if something could be done regarding this matter and the culprit band from using this site as basically it is fraud as someone is using her details to cause trouble. we think we may know who the culprits are iwould i would appreaciate it if you could get back to me asap.
many thanks
Christine Nash
Facebook member