The strange seasonality of violence: Why April is ‘the beginning of the killing season’

Hitler was born in April

Mass-murder researchers and terrorism experts do not like turning their calendars to April. For them, it marks the beginning of what one calls "the killing season."

Timothy McVeigh blew up a federal building in Oklahoma City in April of 1995. Eric Harris and Dylan Klebold killed 13 people at Columbine High School in April of 1999. Seung Hui Cho killed 32 students and teachers at Virginia Tech in April of 2007.

Waco. The Boston Marathon bombing. A mass stabbing in Pennsylvania.

Over the past two decades, April's significance has become a source of concern for those who monitor hate groups and fascination for academics who study the seasonality of violence.

Aggravated assaults spike in summer -- people are outside more and the heat agitates. Burglars take the winter off because people hibernate in their homes. But why would April, with its cheerful tulips and spring sunshine, trigger so much extreme violence?

Timothy James McVeigh, who bombed the Alfred Murray Building in Oklahoma City on April 19, 1995, is escorted from the Noble County Courthouse in Perry, Okla., in this file photo. (DAVID LONGSTREATH/ASSOCIATED PRESS)

"It's a question we talk about all the time," said Heidi Beirich, a domestic terrorism expert at the Southern Poverty Law Center, one of two groups that have issued April-related violence alerts. "It's a really strange phenomenon. We sometimes refer to April as the beginning of killing season."

One of the factors that makes April particularly significant to threat assessment professionals, researchers and others is the desire of killers to pay homage to Columbine, other violent anniversaries and even Hitler's birthday (April 20) by acting on the same date.

"April is a month that looms large in the calendar of many extremists in the United States, from racists and anti-Semites to anti-government groups," the Anti-Defamation League has warned. "Because of these anniversaries, law enforcement officers, community leaders and school officials should be vigilant."

Even the weather may contribute to April's dangers, experts say. The beginning of warm temperatures can stir action among the depressed and socially isolated.

Some researchers question the concept of seasonality. They point out that April is certainly not the only month for carnage. Aaron Alexis killed 12 people at the Washington Navy Yard in September. Adam Lanza killed 20 first-graders and six adults at Sandy Hook Elementary School in December. Jared Lee Loughner killed six and wounded 11, including U.S. Rep. Gabrielle Giffords (D-Ariz.), in January.

"You might say, 'Look, Kennedy was killed in November' and now you look at all the bad things that happened in November and wonder why it's so violent," said David Phillips, a sociologist at the University of California at San Diego who has studied the timing of violence and suicide. "You have to be careful."

But the 30 days of April reveal a particularly gruesome and sensational bunching of homicidal incidents, including some of the worst school shootings in history -- not just in the United States, but in Germany, Brazil and Australia. Martin Luther King Jr. was killed in April. So was Abraham Lincoln.

Obsessed with Hitler

Law enforcement officials hoping to disrupt violent plots have long kept an eye on April as a violence incubator, but there has been surprisingly little empirical study on the issue, perhaps because separating randomness and patterns in violent crime is tricky.

"Connecting these kinds of incidents to any one thing is very difficult," said Mary Ellen O'Toole, a former senior FBI profiler.

A place to start, she said, is motive. Run-of-the-mill street violence is opportunistic and reactive. But terrorism, mass shootings, and other forms of sensational violence typically have political or personal motivations and significance. The killers in those instances are dangerously sentimental, seeking to honor previous evildoers or important moments in history.

April offers an abundance of historical kindling.

Hitler was born April 20, 1889. The Civil War ended April 9, 1865. Patriots' Day, commemorating the first battles of the American Revolutionary War, is April 19. Those dates often coincide with contemporary episodes of mayhem.

On April 19 1993, the FBI stormed a compound in Waco, Tex., to capture David Koresh, the leader of the Branch Davidians sect. Seventy-six people, including Koresh, were killed. Two years later, on the same day, Timothy McVeigh blew up the Alfred P. Murrah Federal Building in Oklahoma City.

McVeigh was a Patriot movement supporter who despised the FBI's actions in Waco, as did other extremists who revere the 19th.

"Tim, why did you go ahead with the bombing?" a psychiatrist asked during an examination.

McVeigh replied: "The date was too important to put off -- the 19th."

Patriots' day. The anniversary of Waco.

"Terrorists consider dates to be very important and symbolic," said Adam Lankford, a University of Alabama professor who studies mass shooters and suicide bombers. "The more attention you bring to a certain date, the more it can snowball."

It certainly did with Columbine. Harris and Klebold reportedly plotted their attack for April 19.

"Harris had mentioned carrying out an attack that was bigger than Oklahoma City," said Peter Langman, a psychologist and writer of two books on school shootings who maintains a database of school shooters and their writings. "The choice of April 19 does not appear to have been random."

But Harris was obsessed with Hitler.

"Hitler and his head boys (expletive) up a few times and it cost them the war," he wrote in his dairies, "but I love their beliefs and who they were, what they did, and what they wanted."

So instead they attacked a day later, Hitler's birthday.

Dozens of other incidents, both disrupted and successful, can be connected to the symbolic nature of April. Columbine is the most frequently cited inspiration of mass shooters, who often seek to time their attacks to the anniversary.

Two years ago, Alex Hribal, a student at Franklin Regional High School near Pittsburgh, wanted to honor the Columbine killers, but school wasn't in session April 20. He struck on Eric Harris' birthday -- April 9 -- and stabbed 20 people.

The fear of April anniversaries is so prevalent that warnings about the month are regularly issued. The Southern Poverty Law Center has sent out alerts about April 19, pointing to "feverish activity" because "it is the most significant date on the anti-government 'Patriot' movement's calendar." Last year, citing the "symbolism and significance of these dates," the Anti-Defamation League issued a security bulletin for April, pointing to Hitler's birthday, Patriots' day, and the 2013 bombings at the Boston Marathon.

The Boston attack, on April 15, raises a knotty question not just about that incident but other high-profile ones in April: Was it symbolically tied to the month -- or just happenstance?

The weather connection

There are no indications that the Tsarnaev brothers were particularly interested in April. They apparently wanted an event where tens of thousands of people would be outside, which generally is not the case during Boston winters. But that raises yet another question about April attacks: Is weather a factor?

Experts say yes, but not just because more potential victims are outside after the long winter. They point to data showing that suicides, often thought to occur mostly in the dreary, socially isolating winter months, actually spike in the spring, starting in April. There is debate about why, although the prevailing explanation is that the increase in sunlight improves mood and energy just enough for suicidal people to make plans and follow through.

"They can muster the energy to do something," said Lankford, the Alabama professor.

The timing of the suicidal spike is important, experts say, because many mass shootings and other violent attacks are thought to be a form of suicide among the socially isolated. Harris and Klebold killed themselves. Cho, the Virginia Tech shooter, killed himself. In April 2009, Jiverly Antares Wong killed himself after shooting 13 people at an immigration center in Upstate New York.

"You have these people coming out of hibernation from the winter with all their anger peaked and ready to go," Lankford said, adding that their rage may build as they see people out having fun together in groups. "That highlights the discrepancies between those who are socially healthy and those who aren't."

Experts on school shootings think that spring's relationship to suicidology could offer another explanation -- besides Columbine -- for why so many of those incidents happen after the winter. Langman's research shows that 46 percent of school shootings end in suicides, with the deadliest events occurring in spring. There were eight school shootings in April last year, the most of any month, according to a database maintained by Everytown for Gun Safety.

Just getting toward the end of the year could also play a role, with stress at its highest and the school year winding down, decreasing the opportunity for an attack before summer break.

Marisa R. Randazzo, the former chief research psychologist at the Secret Service and now managing partner at SIGMA Threat Management Associates, said that requests from schools to help diffuse potentially violent situations spike in April.

"It can be one of the busiest times of the year," she said.

Like other experts, she cautioned that there is no empirical data singling out April as being distinctly different from other months for school shootings or other forms of targeted violence.

The evidence is certainly anecdotal. But there are lot of anecdotes.

April even sank the Titanic.

Copright: Washington Post