Associate editor

The bomber went to prom.

Okay, alleged bomber. As to those who believe the definite article is missing from the sentence above — the prom — my teenage daughters inform me that phrasing is irredeemably antiquated.

Which Dzhokhar Tsarnaev probably knew. Indeed, the intriguing — the chilling — aspect of this 19-year-old is his seeming normalcy.

They are different crimes, spawned by different demons. Yet the Boston bombing and the shootings — at Sandy Hook, Aurora, Tucson, Virginia Tech, the list goes on — somehow meld together.

But with a difference. Look at the pictures of Adam Lanza, James Holmes, Jared Lee Loughner, Seung Hui Cho, and you can imagine the craziness, the disaffection, the just-not-rightness.

Look at Tsarnaev and you see . . . a regular-looking kid, one who — to outside appearances — had, like generations of immigrants before him, assimilated quickly and seamlessly. If he smoked pot, he also volunteered with the Best Buddies program and earned a college scholarship.

He looks like the bad boy in a boy band. His version of wildness: driving his car backward down a one-way street at a prom party — an eerie foreshadowing of the Cambridge, Mass., shootout in which a fleeing Dzhokhar reportedly drove a stolen SUV over his brother, Tamerlan.

“He was just this scrawny little kid who was always giggling and happy,” Juliette Terry, 20, an elementary school friend and part of a group with whom he attended prom, told the Wall Street Journal. “I can’t remember him saying a mean word in his life.”

Larry Aaronson, a high school teacher at Cambridge Rindge & Latin School, told the Boston Globe, “If someone were to ask me what this kid is like, I would say that he had a heart of gold. He was as gracious as possible.”

Those are not the comments you would hear about the school shooters. They had histories of psychiatric problems, previous brushes with the law. Their teachers and classmates understood something was off. When the shootings occurred, those who knew them, or had encountered them, instantly suspected the culprit.

At Virginia Tech, poet Nikki Giovanni insisted that Cho be removed from her class after exhibiting “menacing” behavior, “intimidating” writing and a “mean streak.” In Tucson, Lynda Sorenson, who took an algebra class with Loughner, wrote e-mails before the shooting about “a mentally unstable person in the class who scares the living crap out of me” and describing how she would “sit by the door with my purse handy,” in case he started shooting.

After the Boston bombing, Dzhokhar Tsarnaev went to the campus gym at the University of Massachusetts at Dartmouth, partied with soccer friendsand chatted calmly about the bombing. “He was saying, ‘Yeah, you know, it’s really a tragedy it’s happening right now, it’s a sad thing,’ ” Zach Bettencourt, a fellow student, told NBC News.

Ann Telnaes animation: Senators Graham, McCain and Rep. King call for designating the surviving Boston Marathon bomb suspect as an “enemy combatant.” (Ann Telnaes/The Washington Post)

So remote was the possibility that Tsarnaev was involved that Pamala Rolon, resident assistant in his dorm, told the Globe that, on looking at pictures of the suspect, “We made a joke like — that could be Dzhokhar. But then we thought it just couldn’t be him. Dzhokhar? Never.”

Tamerlan Tsarnaev was a less surprising bomber, showing signs of alienation and radicalization. “I don’t have a single American friend,” he said at one point. “I don’t understand them.” He became increasingly observant of Muslim practices and when the imam at the Cambridge mosque praised Martin Luther King Jr. during a sermon, Tamerlan interrupted, shouting, “Infidel.” His YouTube channel included a song, “I will dedicate my life to Jihad.”

And, as with other terrorists, there were earlier encounters with law enforcement and warning signs, from a domestic violence call to an FBI investigation, prompted by a query request from the Russian security service, of Tamerlan’s interest in radical Islam.

Perhaps we will learn to better identify — and, more important, better handle — the violent mentally ill before they act. Perhaps we will improve at avoiding the dropped ball — the Fort Hood shooter’s intercepted e-mails with Anwar al-Awlaki, the failure to search Zacarias Moussaoui’s laptop before the Sept. 11 attacks. Perhaps Dzhokhar Tsarnaev was uniquely in the thrall of his older brother.

But Islamic radicalism has gone global. You can learn to build a pressure-cooker bomb on the Internet. Sadly, as vigilant as we may be, Dzhokhar Tsarnaev will probably not be the last terrorism suspect who went to prom.

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