Urgent Gmail & Tracing help required! [Harassment]

My friend is being harassed by emails sent from an anonymous gmail account.
It contains personal info and stuff and we have no way how to find who is doing it… I tried looking online but I couldn't find anything so I am posting it here hoping there might be few experts here who could help us.

We only have the e-mail id right now and my friend was saying that she also has the ip address but I don't think it's the correct ip. If anyone can help us, please post here or PM me.