Once you have your 'suspects' are identified you work on the stronger cases via social pressure. As people confess, your algorithm gets more refined. The beauty of the problem is there are a large number of subjects, and a large number of cheaters. It would be fun detective work, except for the fact that that the situation is ethically depressing.
So, actually the problem is fundamentally the same as TSP. It's a distance minimization problem. And just because they use a 'heuristic' doesn't mean that they don't have a solution to the TSP problem. An biologically-based genetic algorithm is no less valid than a computer algorithm.