I'm not sure if this is relevant to what happened to turn Derek Potts into a murderer, but the role of anti-depressants and other mood-altering medications is the subject of this story in the UK's Guardian.
According to the paper, after a man on Paxil for two days shot his wife, daughter and baby granddaughter before killing himself, a US jury found the maker of Paxil (GlaxoSmithKline) liable for $8 million in damages which the corporation had to pay to the surviving family members.
At the bond hearing, the Sangamon County State's Attorney suggested that he heard from Mr. Potts' mother that Mr. Potts was not taking his medicine that treated his bipolar disorder.
We ought to look at whether these chemicals that are designed to alter our minds might have some bad side effects, such as the charge from the doctor in North Wales who said that antidepressant drugs can make people homicidal in the Guardian article.
On a more mundane matter, maybe we should have better social services so if someone gets depressed, they can receive counseling from the government and then take their medication (assuming there aren't any chilling side effects detailed in the Guardian article). That might make us all safer than metal detectors.