I keep getting harassing e-mails from a coworker that appears to be stalking me. Can I take this to the police?

It sounds like you may be a victim of something called “cyberstalking.”

Although there is no universally accepted definition of cyberstalking, the term is generally used to refer to the use of the Internet, e-mail, or other telecommunication technologies to harass or stalk another person. It is not the mere annoyance of unsolicited e-mail; rather, it is methodical, deliberate, and persistent.  Whether from someone known or unknown, the communications do not stop even after the recipient has asked the sender to cease all contacts, and are often filled with inappropriate, and sometimes disturbing, content. Cyberstalking is an extension of the physical form of stalking.

It’s unreasonable to expect cyberstalking victims to walk away from their on-line activities, which may comprise their professional career, in order to avoid this kind of problem.  The response of the law enforcement personnel that you reported these activities to is therefore inappropriate, and you should seek the advice of an attorney who can advise you of your rights.