and I do not know which are correct.
Nowhere did redfearnc say that he downloaded porn on a school computer. It was done at night, so isn't it likely that was on a personal computer? This seems more likely as he said both DSL and dial-up connections were involved, implying two systems; likely DSL at school and dial-up at home. He said his "work" email, which is a school account, had been invaded -- possibly meaning "as well as" his personal computer. It seems that because he mentioned this, the general assumption is that everything was done on a school computer.
There also seems to be an underlying assumption that downloading porn is routine for redfearnc. Perhaps it is, but perhaps he did it just as a test, knowing full well that this was something his "intruder" would pick up and pass on immediately, therefore confirming the source.
With regard to PudgyOne's post: No one can be arrested for "porn" per se, mainly because the Supreme Court did not and could not define what is porn and what isn't -- porn is in the eyes of the beholder. If it were not in the Bible, some would consider parts of Song of Solomon to be pornographic; some would consider many works of Ruebens, Goya, the ancient Greeks and other classic and modern artists to be pornographic because they show nakedness. And how about Michaelangelo's David displaying prominent genitals? Isn't this pornographic to some?
The only truly illegal porn category, for which one can be arrested, is child pornography -- the subjects are under 18 years old. Theoretically, if your mother has a picture of you naked on a bear skin rug, she could be arrested under this law if the police and prosecuter chose to define any nakedness as porn.
On the other hand, if an employer's computer is used for proscribed (but not necessarily illegal) activities, the person may be fired. Downloading porn, even otherwise legal porn, on a school computer almost certainly would fall in that category. They could even have a morality clause in the employment contract making such things as porn downloads reason for termination even if done on a personal computer. This is what redfearnc need to be concerned about, not being arrested.
I agree in general with Mark's assessment. The big key here is if redfearnc was using school computers for illegal or questionable activities. If not, and if no morality clause applies, he probably could safely take legal action against his girlfriend's cousin -- if he is willing to possibly lose his girlfriend.
Here he also needs to ask why the cousin is doing this. There must be some personal reason that the cousin is trying to break up the relationship. How close is the girlfriend to the cousin? Perhaps she could demand the cousin stop, and/or delete all the cousin's e-mails without reading them.
Frank