Some teenagers prank called my mom once. They were very immature that they claim to "threaten" her life. Of course, my mom got pissed off and called the police. Police came and adviced that the best course would be to contact the phone company to get records/block phone numbers, etc.
For my personal advice though, I would contact Google regarding the e-mail incident and see how they would respond. I tried that with Yahoo once and they said I need to get some sort of a police report, a warrant, or a court order and they will happily help me with whatever scary problems I have in regards to e-mail.
I wish you best of luck! I hope you've stepped up security in your life just to be safe.