We are reaching the final stretch of the capital trial of the Boston Marathon bomber, and he is going out with more of a whimper than a bang.

We’ve heard a lot of family drama and seen photos of an adorable little boy and chick-magnet teen.

But we are no closer to understanding what transformed this boy into a terrorist. All the defense case has amounted to is a two-week special edition of “This Is Your Life.” We got to know about him but we never really got to know him.

At this point, it is difficult to hate Dzhokhar Tsarnaev. It would be easier to hate his older brother, Tamerlan, if he were still alive. But it also is hard to care about the kid brother everybody calls Jahar. And someone is going to have to care about him if his life is to be saved.

It just takes one juror to spare him.

But I wonder if anybody on that jury actually does care for him. We saw jurors tear up when his female friends and relatives broke down on the stand. But were they crying for Jahar or his poor, deceived friends?

To care about him, jurors have to know more about who Jahar really is. And they need to understand what went so terribly wrong in his life that he could possibly think bombing the crowd at the Boston Marathon was a righteous thing to do.

They need to know why.

That is going to be difficult because he has been a cipher throughout his trial. We can’t divine what he’s thinking, or even if he is thinking as his defense lawyers present their version of his story. They’ve blamed the bombing and the radical Islam jihad that fueled it on Tamerlan. And they’ve presented Jahar as a cuddly, childlike figure. A tag along.

And so we’ve heard all about his dysfunctional parents and his overbearing big brother, the mastermind of the bombing. We’ve heard how teachers, girls and other people’s dogs went gaga over the mellow boy Jahar.

Because he grew up in an era of ubiquitous cell phones and social media, we’ve seen photos galore of a bright-eyed kid on a school trip to a farm, goofing off in a high school math class, being stared down at a backyard barbecue by an adoring white poodle named Dempsey.

Yes, this question was really asked:

“What was Dempsey’s relationship with Jahar?”

The answer:

“Dempsey really liked Jahar.”

Fortunately, nobody objected to the obvious canine hearsay, and we moved on, eventually coming to Jahar’s wrestling coach, who showed a photo montage of the defendant’s days as a star high school grappler.

He seemed to be a regular kid, which is exactly how his defense attorneys want us to see him. If only Jahar had stayed 8 years old. If only high school could last forever. If only …

But as the defense case winds down, we really are no closer to knowing him. And we may never know why? What turned an adorable little boy and sweet teenager into a hardened wannabe terrorist?

I say wannabe because nothing I’ve heard makes me think he’s the real al Qaeda deal. I think there’s a difference between mass murderers and terrorists. Has Tsarnaev really earned the criminal upgrade? No doubt this was a cruel, senseless, stupid act.

There’s never been any doubt he did it. But at the end of a trial that will determine whether he is executed or spends the rest of his days locked away at a federal prison called Supermax, his defense still hasn’t told us why.

Family drama worthy of Hatfields and McCoys

Everybody really liked Jahar.

The words ring in my ears and I lost count of the number of times people described him as “kind.” He was also called nice, sweet, smart, laid-back, hard-working, polite, respectful and caring. He joined a club called Best Buddies, which came up with activities for special education students. And then he attended the Best Buddies prom.

There is one thing missing from this pretty picture: his parents. Nobody came to his parent-teacher nights at school. They didn’t attend his middle school graduation, although the landlady came. Nobody cheered him on at his wrestling matches. And, at the banquet where wrestlers honor and thank their parents, nobody came to accept a flower from Jahar, the team captain.

That could be the hole that breeds a criminal. Right there, perhaps, is where we see the first beat of an empty heart.

At home, we learned, things were falling apart by the time the youngest member of this volatile family entered high school. Anzor, his father, was having serious psychiatric issues, as his medical records painstakingly documented.

It began as insomnia and panic attacks — post-traumatic stress from being tortured during the Russian-Chechen wars, the jury was told.

But before long Anzor thought the KGB was watching him. He heard voices and sometimes they yelled at him. He saw lizards and animal faces, and sometimes they were fierce.

And then somebody cracked his skull in a parking lot brawl and whatever was going on in his brain only got worse.

“I am very scared,” he told a doctor in October 2009 when Jahar would have been starting his junior year in high school. By then, PTSD had deteriorated into full-blown psychosis. Anzor was barely functioning.

This is not good in a culture with a patriarchal family structure. The patriarch was a walking pharmacopeia, and he told his doctor if he didn’t get better soon, his wife would divorce him. She eventually did, a year or two later. By then, she’d been wearing the pants in the family for a while. Maybe she always had.

They had been a passionate couple, and they had defied social convention by marrying across ethnic lines, members of both sides of the family said. He was of Chechen origin, she was Avar.

Although both were from the mountains of the North Caucasus region, their cultures were distinct. Marrying outsiders was frowned upon.

She was lively and flashy and overtly sexy, wearing short skirts and big earrings. These were not desirable traits in a Chechen Muslim bride. His family despised her and, according to a prosecutor, believed she was a witch.

He was handsome and brawny but grew old and frail before his time. He told people he’d been a prosecutor, but the only work anyone saw him actually do was fix cars.

During a sidebar out of earshot of the jury, prosecutors actually compared the two families to the Hatfields and the McCoys, the famous feuding hillbillies.

But the heart wants what the heart wants, even if the kinfolk disapprove.

“Anzor was crazy in love with Zubeidat, crazy, crazy, crazy in love with her,” said Raisat Suleimanov, a cousin of Jahar’s. She is from his mother’s side of the family, and Zubeidat Tsarnaev’s sisters and nieces traveled from Russia to the United States, where they testified this week for her son. His mother had to stay behind because of an arrest warrant involving a shoplifting incident during her decade in the United States.

The female relatives recalled a sweet boy they knew from family visits. He stayed for months at a time.

Nabisat Suleimanov, another cousin, teared up as she testified, “He was so warm, he was so caring. One would want to hug him and not let him go. He was an unusual child. He was wunderkind.”

He endeared himself to an especially crusty older aunt who did not like children.

“When Jahar appeared, she changed drastically,” the cousin said. “She would even let him urinate in the sink in the kitchen, and it was very strange for us.”

Another aunt, Patimat Suleimanov, was only able to give her name and date of birth before dissolving in tears at the sight of Tsarnaev in court. She sobbed and gasped and hyperventilated before the judge suggested she step down until she could compose herself. She never returned to the witness stand.

But as she cried, she drew out the only glimmer of emotion we’ve seen from the defendant since his trial began in January.

He did not or could not cry for the families of the bomb victims, and he did not tear up when two of his young female friends sobbed loudly over what had become of him. But the sight of an old Russian woman sobbing over him led Tsarnaev to wipe his eyes and dab at them with a tissue.

High hopes, big dreams never materialized

The relatives, along with a former brother-in-law from Anzor’s side of the family, fleshed out the details of the Tsarnaev family’s journey. I couldn’t help but think that if every smart, invisible child in a volatile, itinerant family was fodder for al Qaeda, we’d all be in trouble. I might even qualify.

Anzor and Zubeidat Tsarnaev moved often, sometimes doling out their four children to relatives for months as they got settled in a new place. Each move began with high hopes and big dreams that never seemed to work out. That would be especially true of the move to the United States in 2002.

Jahar was 8 when he accompanied his parents, ostensibly on a vacation. He spent much of his first year in the United States with relatives. Eventually his brother Tamerlan and sisters Ailina and Bella joined them and they settled in a tiny apartment in Cambridge.

Jahar seemed to be the one with the best chance. He adapted easily and appeared headed for the kind of future first-generation immigrants dream of for their children. Even if he didn’t attend Harvard or box for the U.S. team in the Olympics — as his mother boasted Tamerlan would — he’d get along just fine.

The defense spent a lot of time painting Tamerlan, who died during a shootout with police three days after the 2013 bombing, as a colossal failure, an overbearing ogre and the criminal mastermind.

The older brother drank and smoked and dealt marijuana until he and his mother began to get serious about religion. A former brother-in-law said an Armenian stranger named “Misha” seemed to be mentoring him as he tried to be a better Muslim. Misha spent time with Tamerlan and Zubeidat, also teaching them about demons and Satanism.

Anzor thought it all too strange, and fought constantly with his wife, according to a neighbor who ran a video store. But when he came home late from work, eager for a shower, he was told not to walk through his own kitchen so as not to disturb Misha and Tamerlan in their studies.

Former classmate sees ‘betrayal’

Jahar, meanwhile, did what high school kids do. He wrestled, spent time with the Best Buddies and hung out with his friends. If he was getting into religion, nobody in his circle saw it or heard about it.

His high school math teacher knew he was Muslim because he would sometimes hear Jahar and other Muslim students praying in a neighboring classroom. But that was no big deal at a high school that celebrates its diversity.

The math teacher, Eric Traub, gave Tsarnaev a glowing college recommendation in December 2010:

“Dzhokhar is amiable with peers and adults,” he wrote. “His good nature and positive spirit have made Dzhokhar a pleasure to know over the past four years. He is always polite and respectful and enters class with a warm greeting. He is well regarded by his peers and gets along with everyone in class. … ”

Two years later, he was failing at UMass Dartmouth. He’d won a small scholarship and some financial aid, but he was about to lose his ticket.

His parents had finally divorced and returned to Russia separately. Tamerlan journeyed to Dagestan for six months, searching for jihad. Left to his own devices in college, Jahar just hung out, smoking weed and playing video games with his friends.

So what went wrong?

It’s a question the people who knew Jahar Tsarnaev can’t answer. To a one, they were stunned to learn he was the Boston bombing suspect.

“I was shocked when I saw his picture on TV. I didn’t believe it was him at first because it didn’t make sense to me,” said Traub, the math teacher.

“Do you think Jahar had you fooled in high school?” defense attorney Judy Clarke asked.

“No, I don’t.”

A high school classmate who considered herself close to Tsarnaev posted his photo on her Facebook page after his arrest.

Asked how she felt, Rosa Booth, whose family owns Dempsey the poodle, did not hesitate or mince words.

“Betrayal.”

The prosecution will get the final word in this case. That is likely to come next week.

For too long now, we’ve been talking about Jahar. Those photos we’ve seen of Krystle Campbell, Lingzi Lu, Martin Richard and Sean Collier seem to have faded into the background.

And so, one last time, prosecutors will bring back the images truly capable of stirring passion rather than raising questions no one can answer.