How handle stalking and threats from a co-worker via texting?

If this is just slightly weird behavior and you receive the threats, but you feel it's the result of an odd, but inappropriate, sense of humor-- you can just tell the co-worker strait up to quit texting you.  If they refuse and continue with threatening texting, then you have a couple of options.  The least extreme option is just letting your HR Department know what's going on.  More and more companies have "violence in the workplace" policies and they should know that one employee in their facility has been threaten repeatedly by another.  Some people do tend to move on once it's brought to an employer's attention if for no other reason, than just general embarassment.  Your next option for off the job times is to issue the co-worker a criminal trespass warning.  Generally, these are to prevent people from coming to your property, which doesn't seem to be an issue here.  However, criminal trespass warnings that are issued with the assistance of law enforcement do tend to get the attention of some mild stalkers (i.e. they were really serious about calling the law... I should back off now.) 

If you are afraid, however, do not gamble with your safety.  You need to visit with law enforcement and have them make digital copies of the texts that you have recieved.  They may also be able to help you get a protective order, in addition to filing stalking and or some type of harassment charges.  It doesn't matter that the threats come via texting.  What does matter is that someone is threatening you.