Well I think if you have any reason to believe this person is in trouble, or may be suicidal you should contact the local authorities ASAP.

However, if your only concern is that they may no longer be involved in eve, that would be less than productive and probably cause someone undue hassle. It could, in a really extreme example, lead to charges for false reporting (although I don't see that as likely).

I have a suggestion, but it's not quick or easy, nor do I really recommend that you actually do this, but in the interest in sharing information... And it involves abusing the legal system, which you do at your own risk.
That being said... here is how you get his name/address/phone number. File a lawsuit naming JohnDoe 1. Doesn't really matter for what. Pay the filing fee (~50$), and then send a subpoena to CCP asking to identify user XYZ. Assuming they respond and do not dispute the subpoena, you now have his real name, and possibly his billing address if he's ever used a CC to pay. You should also be able to get his IP address last used. Take the name and IP address and file a new subpoena to his ISP asking to identify this user and his contact information. Assuming they respond you now should have his name, address, phone and billing address. Get someone that lives nearby to knock on his door and or call him.
Then drop the court case. (don't forget to do this)

NOTE: doing what I just described is shady as all get out and depending on where you live, and how you use the information, possibly outright illegal. However, it will likely work pretty damn well. Yes, I have done this before, but it wasn't related to eve in any way. ISPs almost always respond to subpoena's quickly and with all the asked for information, no questions asked. I have no idea what CCP will do with one. (they may not even be legally bound to it being that they are not a US based company)

Source: was a paralegal in a past life.