The prize would be based on pessimistic assumptions:
- There are going to be more mass killings. Ways to prevent mass killings are not known.
- Special brain function is needed for the monstrous lack of empathy which enables mass killings without war trauma, or delusionality where the murderer thinks he is an action hero tasked with saving the world by killing masses of nameless goons.
- This brain damage may show up in hormone levels, genes regulating brain function, etc.
- Shooting back is an effective way to stop an ongoing mass killing, for example Hyvinkää shooting stopped after the police returned fire. Effective screening paves the way for responsible and sane armed population. Should mass killers move to illegal guns (most regular gun kills are already done with illegal guns in Finland) then damage control through concealed carry permits is the only effective measure.
Update: The author of the linked article got his statistics wrong. He compares people with gun license killing with guns they own against kills by people without gun license using all methods. Gun kills are just a fraction of all kills, so it is an apples-to-oranges comparison.
Rules for the screening tests:
- The tests can be based on any set of physiological measures like blood sample, genetic profile, saliva, urine, body height, etc.
- The tests consist of a scoring algorithm for calculating pass/fail and a list of physiological measurements.
- The tests can announce false positive for at most 10% of the population.
How prize money would be distributed:
- After a mass killer is caught alive or dead, available physiological measures are taken. This enourages tests, which can be performed on the dead like blood samples, genetic profiles etc.
- After each killing incident, 20% of the prize money is given for the tests which were positive for the killer. 80% remains in the fund for future killings.
- The number of false positives is inversely proportional to the prize money. For example, a test flagging 0.01% of the population earns 100 times more than a test flagging 1% of the population.
- Because of moral hazard, any research team with any links to the killer can't get prize money.
The institute administering the test would have to be international to get adequate sample size. It would also publish all physiological measures about the mass killers, and preferably also from other violent criminals and some voluntary controls without criminal record.
Without trying arrangements like this prize, we'll never know if modern psychology can screen out potential mass killers. What can be lost by trying?