For days after the 2013 Boston Marathon bombing, Americans were glued to the news, eager to know who had planted the homemade devices that ripped through the crowd at the finish line, killing three people.

The world got its first look at the suspects three days after the April 15 attack, when the FBI released surveillance photos showing two men identified only by their baseball caps as "black hat" and "white hat."

The 12-minute film "Jahar" tells a fictional story of how three friends of Dzhokhar Tsarnaev reacted when they realized he was the man in the white hat. It was written by two high-school classmates of Tsarnaev, who was convicted last year of carrying out the attacks and sentenced to death.

Debuting next week at New York's Tribeca Film Festival, the film shows three teenagers trying to understand how the friend they knew by the nickname "Jahar" could have been involved in an attack that wounded more than 260 people, more than a dozen of whom lost legs.

The film, written by Zolan Kanno-Youngs and Henry Hayes, cuts between the friends' memories of hanging out with Tsarnaev, smoking marijuana and laughing, and struggles to accept his role in the attack.

"That's our boy, and just because his picture's up doesn't mean he did shit," one of the friends declares as they argue about news reports linking Tsarnaev to the bombing. "You knew him. When did this man ever talk about politics or bombs or ... terrorism or Islam?"

At his sentencing in June, Tsarnaev admitted to carrying out the bombing with his 26-year-old brother Tamerlan, who died four days later following a gunfight with police. The younger Tsarnaev, now 22, left a note describing the attack as an act of revenge for U.S. military campaigns in countries that are mostly Muslim.

"Jahar" has a very different focus from that of the forthcoming "Patriots Day." That film, about then-Boston Police Commissioner Ed Davis and the hunt for the bombers, stars Mark Wahlberg and is due out in December.

"The pain that we're trying to talk about and the pain that we're trying to convey obviously doesn't relate to that of the actual victims of the marathon bombings, the people who were at the finish line, but it's pain nonetheless," said Kanno-Youngs.

"There's no one way to react to something as bizarre as this."

Some of the teens depicted in the film are angry, but one of them is reluctant to believe Tsarnaev is guilty, clinging to a memory of a young man who talked a police officer into allowing him to drive eight inebriated friends home from a suburban party in an overloaded car.

This screen conflict mirrors history. Former classmates of Tsarnaev appeared in court following his April 19, 2013, arrest, voicing support and denying his guilt. By the end of his trial, his most visible supporters were a handful of anti-death-penalty protesters, who say the sentence he awaits at a maximum security prison in Florence, Colorado, is unjust.

Tsarnaev, an ethnic Chechen, and his family came to the United States a decade before the attacks, settling just outside Boston in Cambridge, Massachusetts. His parents failed to thrive and eventually returned to Russia, but Dzhokhar remained, living with his brother and becoming a high-school wrestling star.

Hayes, who also directed the film, said he hoped it would prompt people to analyze what set Tsarnaev on the path to violence.

"It's important that we not close ourselves off from these questions because things like this keep happening," Hayes said. "If we're not thinking about why - why do things like this happen - we're doing ourselves a disservice, a potentially fatal disservice."

(Reporting by Scott Malone; Editing by Lisa Von Ahn)