The 1999 attack at Columbine High School opened a new chapter in America's modern history of mass murder.Thirteen people were shot to death -- two dozen were wounded -- by two high school boys. The media linked the shooting to violent video games.But buried beneath the Washington Post headlines was the detail about Eric Harris' treatment with the antidepressant Luvox. Fourteen years later, claims of a link between anti-depressants and violence have grown louder, if not clearer. British psychiatrist Dr. David Healy told WPBF 25 News that "almost all the school shooters that we know of have either been on or using these drugs or in withdrawal from them."Healy is a leading voice in the call for stronger warnings about anti-depressants, specifically the withdrawal from the group of drugs called Selective Seratonin Reintake Inhibitors, or SSRI.Last July 20, James Holmes walked into a midnight showing of the latest "Batman" movie in Aurora, Colo., and opened fire, killing 12 and wounding 58, police said. The Denver Post reported Holmes was taking generic Zoloft, an SSRI."You can become emotionally numb when you go on these drugs," Healy said. "That means you can do things you wouldn't normally contemplate doing."The truth about the drugs may be elusive. Within days of the mass killing of children and teachers at Sandy Hook Elementary School in  Newtown, Conn., speculation rose about shooter Adam Lanza, his mental state and possible use of anti-depressants. A man emerged claiming to be Lanza's relative and blamed anti-depressants. He disappeared, an apparent fraud. And initial reports in 2007 -- including one from CBS News -- linked Virginia Tech mass murderer Cho Seung-Hui to anti-depressants. But State police later confirmed Cho had no anti-depressants in his system.Few doctors deny the help SSRIs provide depressed patients: Paxil, Prozac, Zoloft, Effexor and the rest. Doctors also acknowledge there's something called SSRI Discontinuation Syndrome. A simple Google search of "SSRI Withdrawal" yields dozens of results, including a link to a site called usahitman.com. All offer claims, cases and opinions, and purport to have proof that links mass killers to antidepressant withdrawal.Boca Raton psychiatrist Dr. Abbey Strauss has a very different view of those claims. He said he believes the theory is too simplistic. "Too often people like to assume," Strauss said. "They project a little bit of logic, and they say ... that could theoretically explain a large problem. That's faulty logic. So many people abruptly stop their medications and we don't have an equivalent number of people going out and committing crimes."In fact, according to the New York Times, after Jared Loughner pleaded guilty to killing six and wounding nine in the 2011 attack in Tucson, Ariz., that severely injured Rep. Gabby Giffords, he told his doctor he wished he had taken the anti-depressants he had been prescribed long before the shooting. But Healy pointed to side effects we may not be told about, or effects some doctors may not believe."You can hear a voice, you can for instance hear the voice of God saying, 'Kill that person,' even though you don't know him," Healy says, "'because I'm God and I know he's thinking about trying to kill you.'"Strauss doesn't buy it."I've had a few people say they were uncomfortable or they felt antsy, more irritable or something else," he said. "It never rose to the level of violence."Strauss and Healy agree that the key to prescribing SSRI anti-depressants is proper diagnosis and close doctor-patient communication. Healy added such drugs are not simply "vitamin Seratonin" that you can give a patient so he or she can walk away cured."Doctors once were much better able to listen to patients and work out with them whether a drug is causing a problem or not," Healy added. "They've since, for the last 25 years, gone by what the clinical trials published in journals (say), or said we have to wait to hear what the FDA says."