Monday's bomb scare at Harvard was perpetrated by a sophomore "motivated by a desire to avoid a final exam..."
Even though Eldo Kim, 20, used the Tor network, in conjunction with an anonymous email service Guerilla Mail, to hide his location and identity, the FBI didn't have a lot of trouble locating him because he used the Harvard wireless network to send the threat. Some of the details of his critical error are spelled out in an affadavit filed by FBI Special Agent Thomas M Dalton in support of an arrest. The fact that the threats came on the day of finals was a good indicator that a student was responsible.
The affadavit doesn't give details on how he was traced, and it worked to a point. But the FBI and school IT were able to determine who was using that software at the time the emails were sent. That pointed to Kim's login.
Hat tip to On The Media.