Effexor is Wyeth's best-selling drug, by the way, which in one recent year brought in over $3 billion in sales, accounting for almost a fifth of the company's annual revenues.

And what exactly does "rare" mean in the phrase "rare adverse events"? The FDA defines it as occurring in less than one in 1,000 people. But since that same year 19.2 million prescriptions for Effexor were filled in the U.S., statistically that means thousands of Americans might experience "homicidal ideation" – murderous thoughts – as a result of taking just this one brand of antidepressant drug.

Paxil's known "adverse drug reactions" – according to the drug's FDA-approved label – include "mania," "insomnia," "anxiety," "agitation," "confusion," "amnesia," "depression," "paranoid reaction," "psychosis," "hostility," "delirium," "hallucinations," "abnormal thinking," "depersonalization" and "lack of emotion," among others.The preceding examples are only a few of the best-known offenders who had been taking prescribed psychiatric drugs before committing their violent crimes – there are many others.

Whether we like to admit it or not, it is undeniable that when certain people living on the edge of sanity take psychiatric medications, those drugs can – and occasionally do – push them over the edge into violent madness. Remember, every single SSRI antidepressant sold in the United States of America today, no matter what brand or manufacturer, bears a "black box" FDA warning label – the government's most serious drug warning – of "increased risks of suicidal thinking and behavior, known as suicidality, in young adults ages 18 to 24." Common sense tells us that where there are suicidal thoughts – especially in a very, very angry person – homicidal thoughts may not be far behind. Indeed, the mass shooters we are describing often take their own lives when the police show up, having planned their suicide ahead of time.

So, what 'medication' was Lanza on?

The Sandy Hook school massacre, we are constantly reminded, was the "second-worst school shooting in U.S. history." Let's briefly revisit the worst, Virginia Tech, because it provides an important lesson for us. One would think, in light of the stunning correlation between psych meds and mass murders, that it would be considered critical to establish definitively whether the Virginia Tech murderer of 32 people, student Cho Seung-Hui, had been taking psychiatric drugs.

Yet, more than five years later, the answer to that question remains a mystery.

Even though initially the New York Times reported, "officials said prescription medications related to the treatment of psychological problems had been found among Mr. Cho's effects," and the killer's roommate, Joseph Aust, had told the Richmond Times-Dispatch that Cho's routine each morning had included taking prescription drugs, the state's toxicology report released two months later said "no prescription drugs or toxic substances were found in Cho Seung-Hui."

Perhaps so, but one of the most notoriously unstable and unpredictable times for users of SSRI antidepressants is the period shortly after they've stopped taking them, during which time the substance may not be detectable in the body.

What kind of meds might Cho have been taking – or recently have stopped taking? Curiously, despite an exhaustive investigation by the Commonwealth of Virginia which disclosed that Cho had taken Paxil for a year in 1999, specifics on what meds he was taking prior to the Virginia Tech massacre have remained elusive. The final 20,000-word report manages to omit any conclusive information about the all-important issue of Cho's medications during the period of the mass shooting.

To add to the drama, it wasn't until two years after the state's in-depth report was issued that, as disclosed in an Aug. 19, 2009, ABC News report, some of Cho's long-missing mental health records were located:

The records released today were discovered to be missing during a Virginia panel's August 2007 investigation four-and-a-half months after the massacre. The notes were recovered last month from the home of Dr. Robert Miller, the former director of the counseling center, who says he inadvertently packed Cho's file into boxes of personal belongings when he left the center in February 2006. Until the July 2009 discovery of the documents, Miller said he had no idea he had the records. Miller has since been let go from the university.

Although Cho's newly discovered mental-health files reportedly revealed nothing further about his medications, the issues raised by the initial accounts – including the "officials" cited by the New York Times and the Richmond paper's eyewitness account of daily meds-taking – remain unaddressed to this day.

Some critics suggest these official omissions are motivated by a desire to protect the drug companies from ruinous product liability claims. Indeed, pharmaceutical manufacturers are nervous about lawsuits over the "rare adverse effects" of their mood-altering medications. To avoid costly settlements and public relations catastrophes – such as when GlaxoSmithKline was ordered to pay $6.4 million to the family of 60-year-old Donald Schnell who murdered his wife, daughter and granddaughter in a fit of rage shortly after starting on Paxil – drug companies' legal teams have quietly and skillfully settled hundreds of cases out-of-court, shelling out hundreds of millions of dollars to plaintiffs. Pharmaceutical giant Eli Lilly fought scores of legal claims against Prozac in this way, settling for cash before the complaint could go to court while stipulating that the settlement remain secret – and then claiming it had never lost a Prozac lawsuit.

All of which is, once again, to respectfully but urgently ask the question: When on earth are we going to find out if the perpetrator of the Sandy Hook school massacre, like so many other mass shooters, had been taking psychiatric drugs?

In the end, it may well turn out that knowing what kinds of guns he used isn't nearly as important as what kind of drugs he used.

That is, assuming we ever find out.

