If you have been threatened via email or via a talk/chat/irc session, you should immediately call University of Rochester Security (x13) just as you would for a threatening or obscene phone call.
This is especially true if the threat is local. A threat from someone in another state needs to be taken seriously, but it takes some time for them to get to Rochester to execute the threat. In such cases, it may be more appropriate to contact UR Security using the non-emergency phone number.
You should also contact the systems staff via mail (to problem ) or by phone, or in person. When you contact security, please give them the names of the systems staff, and indicate that the systems staff are willing and able to work with them.
If you are threatened via mail, save the mail. If someone used talk, irc, or write or any other communication program to threaten or harass you, please try to capture that information. If you cannot cut and paste from your screen, you need to at least try to write down the hostname and any user name information available. The time and date are also important pieces of information to record.
Often the harassing individual wants to provoke a reaction from you. By reacting, you are playing the harasser's game; don't let them win. Getting into an argument with them, and so on, is counter-productive. The systems staff can deal with the user directly if they are local, or we can contact the administrators at a remote site if they are not local.
Threats and harassment are not the same. Threats should always be passed on to security. It is less clear with harassment. If you are unsure if you are being threatened or harassed, err on the side of notifying security. If it makes you uncomfortable, it is best to get the problem into the system. If it becomes more aggressive, you have already started the paper trail needed to assist security in terminating the harassment.