There are some mental illnesses which come with the potential for extreme violence. I'm not talking the sociopath here who kills without remorse, but those mentally ill people while in the throes of their delusions who are driven to kill. The outcomes can be horrific.
On December 6, 1989, a lone gunman gunned down fourteen women at a Montreal college. The feminist movement (the liberals so lambasted on this board lately) picked this up as a symbol of "hatred against women". This bothered me deeply because the lesson at the college is not that all men wish to kill women, but that a single, mentally unstable gunman managed to slip through the cracks in hour mental-health care system. Killing women is just crazy. By targetting the wrong group - all men - the real problem is left unresolved. We don't have adequate resources to identify and treat mentally ill people.
http://www.cbc.ca/archives/categories/society/crime-justice/the-montreal-massacre/gunman-massacres-14-women.html
On July 30, 2008, Vince Li beheaded fellow passenger Tim McLean on a Greyhound bus. Mr. Li has been incarcerated in a mental institution ever since. Many Canadians would have preferred the death sentence for this horrific act, and any application for day passes makes the news. Mr. Li at the time felt he was defending himself against his alien tormentors. I have sympathy for the whole tragic unfolding of events, as Mr. Li has the same mental illness as my son. I have heard my son relate his own terrors, and I along with his mental health team do our best to convince him to live in peace, regardless of the sinister intent of the incessant voices.
http://en.wikipedia.org/wiki/Killing_of_Tim_McLean
Certainly propogandizing our planet with the news that we are not under attack by hostile aliens, would have little effect. Metal detectors at bus stations may help. But again, I think the issue is with poor identification and treatment of mental illness in this country. I think it is the best way to prevent future events.
Now we have a beheading in Oklahoma by a crazed knife-weilding co-worker, Alton Nolen. He also happened to be a recent convert to Islam.
http://en.wikipedia.org/wiki/Vaughan_Foods_beheading_incident
Is the problem the violent nature of the Islamic writings? Or is it anti-feminist rhetoric? Or perhaps too many alien sightings? Crazy is crazy, and it barely needs any signal from the outside world to ignite.
I'll bet anything that Alton Nolen went and gone postal.
http://en.wikipedia.org/wiki/Going_postal