That there is one part of a persons genetic make-up responsible for them committing murder, that it would be possible to breed out of them, or switch off, is bad science of the worst sort.
What about nurture, environment, and other outside influences? Want to control those as well?
Genetic manipulation is not an ethical solution to the world's ills. radamfi, you sound too much like an early 20th century eugenicist.
Your points may only be a of a philosophical nature. However, implementing them, even if possible, is, to my mind, not the the start of the road to utopia, where human suffering, pain and strife is eradicated, but a quick slippery slope into a dystopian nightmare.