I caught students cheating on tests. What I did was, first, I asked them why. Get them to talk of their real problems behind the act, and get them to retake the test.
Many will say I'm lenient, but I want the students to learn and understand that while their act is wrong, yet I understand their plight...even those that seemed to be 'irresponsible' reasons (like gaming late, doing other stuff, etc.) Always tell them I never 'removed' the student in me.
Also, I always catch cheaters. By eye movements, sitting arrangement, posture and behaviors, tapping of pens, coughing patterns, and even the position of the paper on the table. lol