The school’s IT director took a shine to the challenge. Long story short: Using the time-frame of the comments, our website location and the IP addresses in the WordPress e-mail, he tracked it back to a specific computer. The headmaster confronted the employee, who resigned on the spot.
Why do people assume the teacher quit because he thought he'd get fired? If I had a boss come to me at the end of the day and say the IT department has spent all day stalking someone who anonymously used the word "p*ssy" as a joke about eating and now it's been discovered that I am the culprit with any kind of incriminating tone I would quit too.
Real computer scientists like having a computer on their desk, else how could they read their mail?