With one suspect dead and the other hindered in his ability to communicate, investigators are eager to speak to Tamerlan Tsarnaev's wife, Katherine Russell, to see what she might know about incidents leading up to the bombings.
On Monday, her attorney said she learned of her husband's alleged involvement through news accounts.
"She knew nothing about it at any time," Amato DeLuca said in response to questions about whether Russell knew of plans to attack the marathon.
Tsarnaev stayed home and cared for the couple's 2-year-old daughter while his wife worked long hours as a home care aide, according to DeLuca.
The family is devastated, the attorney said.
"They're very distraught. They're upset. Their lives have been unalterably changed. They're upset because of what happened, the people that were injured, that were killed. It's an awful, terrible thing," he said. "And of course Katy, it's even worse because what she lost -- her husband and the father of her daughter."
Police chief: The carnage could have been worse
In the tumultuous days after the bombings, the Tsarnaev brothers allegedly killed a university police officer, led authorities on a harrowing chase and hurled explosives at police, authorities said. Another officer, seriously wounded in a firefight with the suspects, was recovering Monday, Boston Police Commissioner Ed Davis said.
The brothers -- armed with handguns and explosives -- apparently were planning another attack before a shootout with police disrupted their efforts, Davis said.
"I believe that the only reason that someone would have those in their possession was to further attack people and cause more death and destruction," Davis said on CNN's "Starting Point" Monday.
Authorities believe the brothers bought bomb components locally but think that their guns came from elsewhere, another federal law enforcement official said. The official, who was not authorized to publicly discuss the case, said authorities are trying to trace the guns.
Investigators are also trying to determine whether anyone else was involved in the bombings.
But Davis, speaking Sunday to CNN's Don Lemon, said that he was confident that the brothers were "the two major actors in the violence that occurred."
"I told the people of Boston that they can rest easily, that the two people who were committing these vicious attacks are either dead or arrested, and I still believe that," the police chief said.
Details on shootout
The wild shootout that prompted the dramatic lockdown of the Boston area Friday began after a single officer gave chase after encountering the stolen car the brothers allegedly were driving, Watertown police Chief Edward Deveau told CNN's Wolf Blizter on Saturday.
According to Deveau, the brothers stepped out of the car and shot at the officer, who put his car in reverse to get away from the gunfire.
More officers arrived, sparking a firefight that lasted five to 10 minutes. More than 200 shots were fired, and one of the brothers threw explosives at police -- including a pressure cooker bomb similar to the one used at the marathon, Deveau said.
Eventually, Tamerlan Tsarnaev emerged from cover and began walking toward officers, firing as he went, the chief said.
When he ran out of ammunition, officers tackled him and tried to handcuff him, Deveau said Saturday.