https://www.researchgate.net/publication/259270974_The_2-Repeat_Allele_of_the_MAOA_Gene_Confers_an_Increased_Risk_for_Shooting_and_Stabbing_Behaviors
This was the closest I could get: https://go-beyond.org/decensor/info/84e6f88f986ebd9060e0ed7f4cbe697813a3e423da141b3a830dc631e9284cf4
(post is archived)