There are several questions to be answered here and a lot of people are concerned about their security on the Net. Can the Internet kill you? Directly, it cannot, that's for sure! What about people threatening your life?
Bogus!
Now, can the Internet be used to kill? Well, not as a tool, but as an environment, yes! And I'll give you two examples here - there are a lot of serious things handled on the Internet or on computers that are connected to it. Spammers send lots of medicine-related messages and how you can get drugs really cheap from their online shops. Those drugs could get you killed! You need to see a real doctor and get a prescription, if you have medical issues, not buy crap advertised through spam! Also, imagine what a denial of service could do to a hospital that uses computers to keep track of important patient data! These threats are not something common, for you to worry too much, but they exist and should be taken into consideration! That's why you need to ignore spam and deploy security measures on the computer!
Another thing - everybody is Braveheart on the Web. People take advantage of the anonymity the Internet provides them with and will go as far as threatening other users with death. If you ever get an e-mail that threatens your life and asks for a ransom, don't even consider it - it's all a sham.
Web-related death is something I've never seen in my life… well, except for those crazy kids that spent days in front of the PC and then died, but that has nothing to do with whatever is going on over the Net. I hope I've made things a bit clearer now, for anyone that had a different opinion about it.