He was just a year older than the Boston Marathon bomber when he sentenced him to death

At age 22, most Americans don't yet have a lot of weighty responsibilities.

Kevan Fagan spent that year of his life living with his parents, taking a break from college and working a part-time job at Best Buy. 

Then the Massachusetts resident received a summons. He was chosen to serve on the jury that heard the case against Boston Marathon bomber Dzhokhar Tsarnaev and ultimately sentenced him to death.

Fagan says throughout the trial, he saw things he could relate to in the life of 21-year-old terrorist. "I definitely saw some of the young adolescent kid, " Fagan says. "Being a little bit more rebellious and not being so thoughtful and being a little haughty or staunch. It reminded me a little of myself."

But Fagan is quick to add, "He still did that act, he put a bomb down during the marathon." 

Fagan was the youngest juror among the 12. He's writing a book about the experience with a family friend Amir Bavar. It's called Juror 83 — The Tsarnaev Trial: 34 Days That Changed Me. 

Fagan has had some counselling services to help him process what he saw and heard in the court proceedings, and to grapple with the decision to sentence a man to death. He admits that he's learned things since the trial ended that might have impacted his decision. Fagan, for instance, hadn't been aware that the family of the youngest bombing victim, 8-year-old Martin Richard, had written an essay in The Boston Globe, laying out why the couple preferred Tsarnaev not receive a death sentence. . 

Fagan says he was deeply affected by hearing that news after the trial.  "Yeah, of course, had I known that, would I have thought a little bit differently?" Fagan says. "Yes."

Tsarnaev's attorneys appealed their client's death sentence last month. They argued that publicity had made it impossible for Tsarnaev to receive a fair trial in Boston, where the attack occurred in April 2013. 

Fagan says the lawyers' appeal makes sense to him. But he adds, "Where ever you go, especially with the Internet and social media, and exposure, across the country, it would be really hard to find one group of people who really knows nothing (about the case)."

He says he still thinks about Dzhokhar Tsarnaev.

"I kind of saw him as a disheveled, frail sort of person," Fagan recalls. "He definitely looked like a kid who was existentially lost."