It’s not that the women, the mothers, don’t blame both brothers Tsarnaev as law enforcement officials continue to investigate the bombings at the Boston Marathon and its aftermath, horrors that killed and maimed. There is no limit to the anger and rage aimed at the two of them.

But while the back story for the older brother, 26-year-old Tamerlan, provided a simplistic explanation that made it easy to keep him at a distance, 19-year-old Dzhokhar’s is a different American tale.

In this undated photo provided by radio host Robin Young, Dzhokhar A. Tsarnaev, left, and Young’s nephew pose for a photo after graduating from Cambridge Rindge and Latin High School in Cambridge, Mass. (Robin Young/AP)

Tamerlan’s journey followed a pattern we’ve gotten used to, hardened by – alienation and a change in personality, an overseas trip, radicalization, videos praising Islamic jihad. Past charges of domestic violence against him added to the picture we think we know. In contrast, Dzhokhar went to the prom. It’s hard to imagine an 8-year-old, his age when he moved to the U.S., joining a sleeper cell. As a teenager, he qualified for the wrestling team and a college scholarship.

The puzzled women who stopped me at the gym and the market weren’t looking for an excuse, just an explanation. He was so American, they said, with his sweats and backward-turned cap. I knew exactly what they meant. Dzhokhar attended the same kind of high school my son did — public, diverse and full of high achievers. He could have been the kid who passed through my kitchen for a super-sized snack before the next practice for debate, cross country or Odyssey of the Mind competitions.

Not only did he have it all, it seemed, he had more than a lot of kids his age. His classmates and friends from Cambridge Rindge and Latin in Cambridge, Mass., struggled even after his deadly attempted getaway and arrest to emphasize his friendliness; they tried to figure out what they missed in his alleged turn from cool kid to cold-blooded killer. Ty Barros, 21, a former high school classmate, said: “He was a fairly popular kid; he was a fairly friendly, nice kid.”

“He was one of those people you could confide in and he always offered help — do you need food? are you hungry? — like a friend would do,” said Pamala Rolon, the residential adviser in his UMass-Dartmouth dorm.

What was striking was how ordinary the 19-year-old sounded in recollections. Sure, he was shy, said friends, but no one used the “alienated loner” profile most often heard when teens turn a gun on the classmates they have known for years.

The attempts to explain, from his parents’ return to far-away Russia to an idolized brother’s influence, did not seem enough. What was missed? What could have been done? In his privileged American life, what could have gone wrong?

In death, Tamerlan Tsarnaev is still under investigation, and no one will know his complete story for a while. But enough of it fits a certain narrative to give the illusion, at least, of understanding. In contrast, the life experience of American citizen Dzhokhar Tsarnaev is too close for comfort.

As he remains under heavy guard in a Boston hospital, federal and local authorities wait to question the teen, who suffered gunshot wounds to the neck.

For security reasons, the priority will be discovering additional violent plots and accomplices, if they exist.

Ultimately, though, like the bewildered mothers who continue to share their questions, everyone will want to ask Dzhokhar Tsarnaev how his American dream turned so sour. They will want to know “why.”

Mary C. Curtis, an award-winning multimedia journalist in Charlotte, N.C., has worked at the New York Times, Charlotte Observer and as national correspondent for Politics Daily. Follow her on Twitter: @mcurtisnc3