A Desktop Lock utility with Webcam Capture.

Basic function is: monitor keyboard and mouse input. After a brief pause (1-2 minutes), soft-lock the desktop. Unlock happens with a series of mouse clicks, combined with ALT and CTRL key presses. If more than a little input is detected while locked, or after repeated failed attempts at unlocking, start the webcam to capture the person who is operating the keyboard, who presumably is unauthorized.

Ostensibly a security utility, this program is aimed at casual use, such as if you suspect your coworkers are messing with your system, and you want to find out who it is. It is not robust enough to be a substitute for any real protection of your system. It is compatible with, and makes use of, the Windows desktop hard locking feature. (Using 'soft' and 'hard' locking here to distinguish between the Wingotcha lock from the Windows desktop lock).