why don't you contact the internet providers first.
My name is Stephen R. Cohen and have practiced since 1974. I practice in Los Angeles and Orange County, CA. These answers do not create an attorney client relationship. My answers may offend I believe in telling the truth, I use common sense as well as the law. Other state's laws may differ.. There are a lot of really good attorneys on this site, I will do limited appearances which are preparation of court documents it is , less expensive. However generally I believe an attorney is better than none.
The reality is that most cease and desist letters aren't worth the paper they are printed on. A local internet attorney can be retained to subpoena the internet service provider and go from there.
The laws regarding stalking and harassment are usually determined by the state in which you live. You could sue DOES for emotional distress and then your attorneys can obtain subpoenas which they can serve on the internet providers with the requisite information required by your state law, requesting documents showing the identities of the stalker. Unfortunately, most of the internet providers that are involved will be out of state, so you will have to retain attorneys in the states in which the internet providers are located in order to properly serve a subpoena on that provider. It is timely and costly. Regardless, in this type of situation it is highly unlikely that a cease and desist letter would work. Good luck.
A roundup of the best tips and legal advice.