Though a suspect is in custody and charges have been filed, authorities haven't nailed down the motive in the Boston bombings, but they're pretty sure the attack was motivated by religion, specifically "a radical brand of Islam." On Monday night, multiple reports and government documents combined to shed new light on the investigation into Tamerlan and Dzhokhar Tsarnaev's alleged roles in last week's terrorist attack. The new information doesn't make either brother looks less guilty — or suggest that much could have been done to stop them.

First, there's Dzhokhar and his extraordinary bedside hearing. During the questioning at Beth Israel Deaconess Hospital in Boston, the 19-year-old managed to tell his side of the story with just two nods and a single word. He also wrote on a pad, but authorities haven't made those statements public yet. We do know that Dzhokhar nodded once to indicate that he could answer some questions and again to acknowledge his Miranda rights. Dzhokhar later said just one word during the hearing: "No," to indicate that he could not afford an attorney, despite the fact that his mother earlier indicated that one of his uncles, "a big oil lawyer," was helping with the legal side of things.

The most incriminating statement may not have come from Dzhokhar's hospital bed, however. It may have arrived during Thursday's night of mayhem. According to the victim of the carjacking, one of the brothers tapped on the victim's window and reached in to open the door when the car's driver rolled it down. "The man pointed a firearm at the victim and stated, 'Did you hear abut the Boston explosion?' and 'I did that,'" the criminal complaint explains. "The man removed the magazine from his gun and showed the victim that it had a bullet in it, and then reinserted the magazine. The man then stated 'I am serious.'" (In an interview Monday with NBC News, the unnamed carjacking victim called the brothers "brutal and cautious.")

So the brothers knew what they were doing to a certain extent. And the narrative of Dzhokhar's alleged role in the attack and aftermath will play out when he's on trial in the coming days and weeks. His next court date is set for May 30, when we'll probably learn more about an as yet unreleased surveillance video in which he slips off his backpack — and footage, described in an FBI affidavit released with the charges, in which "[v]irtually every head turns to the east (toward the finish line) and stares in that direction in apparent bewilderment and alarm. Bomber Two, virtually alone among the individuals in front of the restaurant, appears calm. He glances to the east and then calmly but rapidly begins moving west, away from the direction of the finish line."

More challenging, however, is the quest to better understand Dzhokhar's late older brother Tamerlan and his recent history of religious fervor and even violence. A separate AP report offers some insight. Tamerlan was religious, apparently more religious than his little brother — or at least, he was more vocal about his beliefs. The leader of a Cambridge mosque, where the two sometimes went to services, revealed that Tamerlan had caused multiple disruptions during service. In one incident that took place last January, the 26-year-old brother stood up in the middle of a sermon about Martin Luther King Jr. and called the preacher a "non-believer" and "hypocrite" who was "contaminating people's minds." This outburst led to Tamerlan's being heckled out of his local mosque as recently as January.

It's seems increasingly apparent, as the "million questions" begin to get answers, that if the Tsarnaev brothers were indeed behind the attack, then Tamerlan may have been the ringleader. The mosque outbursts weren't the only warning sign either. Russian security services flagged the elder Tsarnaev two years ago after he attended services at a radical mosque in Dagestan. The same mosque has seen a number of terrorists pass through its doors, including those behind a 2002 explosion in Kaspiysk that killed 44 people. It is perhaps because of this link that Tamerlan's name, however misspelled, found its way onto an FBI watchlist. Tamerlan's dark history, the media has learned, also includes allegations of domestic abuse and a possible connection to a triple murder. The most obvious warning sign of all — the 2011 request from the Russian government, telling the FBI that Tamerlan "was a follower of radical Islam" — couldn't even legally lend itself to followup. As The New York Times reported Monday night, "a limited investigation" is all that warning sign could foster.

You see, warning signs are tricky things. Despite the fact that the brothers' mother says her elder son had been in contact with the FBI for years — among those other warning signs — even Tamerlan's wife still couldn't believe that her husband was involved in the Boston bombings. "She couldn't believe it," the lawyer for Katherine Russell says. "She was in complete shock." Same goes for his ex-girlfriend, the one involved in a 2009 domestic abuse complaint against Tamerlan: "He was a little tough guy, but I thought that was it," Nadine Ascencao told The Wall Street Journal Monday evening. "In high school, everybody acts like that. Like a bully guy, you know? Now it's just shocking for me.”