Katherine Russell, Tamerlan Tsarnaev's widow, remained largely out of view this week inside her parents' home. It remains unclear what, if anything, what she might have known or suspected.
According to her attorney, Amato DeLuca, the 24-year-old widow knew nothing of plans to bomb the race, and reports of her husband's involvement came as an "absolute shock" to Russell and her family.
But two sources familiar with the investigation told CNN that she spoke to her husband after his picture appeared on national television as a suspect.
The nature of the conversation remains under investigation, but the sources said there was some concern that Russell spoke with her husband but did not call authorities who were still seeking to identify the men in the photos.
The driver who was held hostage by the Tsarnaev brothers for 90 minutes before police caught up with them, spoke to CNN this week.
The man, who CNN is describing only as Danny because of privacy and safety concerns, said there was a difference of personalities between the brothers.
Tamerlan Tsarnaev kept talking throughout the ordeal, barking out orders, detailing his hatred of Americans and asking Danny to remain calm.
"If you cooperate, I won't kill you," said Tamerlan Tsarnaev, according to Danny.
While the talkative Tamerlan was the ringleader during the carjacking, the quiet Dzhokhar responded to multiple orders, such as getting money from an ATM, he said.
An uncle of the brothers claimed that a man known as "Misha" was responsible for radicalizing Tamerlan Tsarnaev. On Monday, a U.S. government official told CNN that FBI agents had interviewed Misha.
The man, whose real name is Mikhail Allakhverdov, denied ever encouraging a violent take on Islam and says he was not Tamerlan's teacher, according to a New York Review of Books writer who says he interviewed Misha.
Of the scores of people injured in the blasts, 17 remain in five Boston-area hospitals, though none is in critical condition, according to information the hospitals provided to CNN.
Bombing survivor Jarrod Clowery told a news conference how impressed he was by the first responders who helped him and so many others and how coordinated they were -- even better than the best drive by New England Patriots quarterback Tom Brady.
"No disrespect to Tom Brady, I love him, but he can't hold a candle to [those] people," he said.
One of the biggest questions is whether federal intelligence officials could have done more to prevent the attacks.
"Based on what I can see so far, the FBI performed its duties. The Department of Homeland Security did what it was supposed to be doing," President Barack Obama said this week. "But this is hard stuff."
An independent review by the Intelligence Community inspector general is under way.
James Clapper, the director of national intelligence, believes that all of the agencies involved in collecting and sharing information about Tamerlan Tsarnaev "took all the appropriate steps," Clapper spokesman Shawn Turner said.