The 28-year old private tutor Timothy Lance Lai of Irvine, provided the students with a hardware keylogger device and showed them how to use the device, according to local news report.
Hardware Keylogger is a small device that can be plugged in between the keyboard and CPU, capable of capturing the keystrokes. Most of time it is hard to detect a hardware key logger, as they are plugged in the back of a computer and no antivirus software detect them.
The students plugged in school computer and leave it there and retrieve it after few days so that it will capture the login credentials of staffs. At least, 17 teacher's computer has been hacked.