This is a great pyramid system,i.e.:
The first person caught would have the best chance to reduce their prison time because they would become active trying to track offenders first. The person he or she turned in, would have to try to find remainding offenders before the first person did because only one person could get credit for stopping another offender! As more criminals are caught, there would be less for the latest criminal caught, to find, for reducing THEIR sentence.
Fr example,: If they each turned in only one a day, the second day, 2 people would be caught, then 4, then 8, 16, 32, 64, 128, etc. That's one week of time. It doubles the total number of possiblities each day for someone new to be caught, thereby reducing each criminal's odds, by half from the previous day, to reduce their sentence. They would really have to scramble to find new offenders before their competing offenders did.
In addition... "There is no honor among thieves", and it would be "Every man for himself!!"
You gotta love the possibilities.