2). Snap some candid photos of them in public
3). Threaten to make a myspace profile in their name unless the pay up
Putting cameras in their homes might be better than sending them to jail.
In the US, we have a nice little thing called due process, which guarantees (or at least it used to) that, before a person could be deprived of their rights in such a way as having a camera installed in their home, they are entitled to a fair and impartial trial by a jury of their peers.
To spot the expert, pick the one who predicts the job will take the longest and cost the most.