Two U.S. officials told the Associated Press on Monday that evidence suggests the suspects in the Boston Marathon bombing were motivated by religion and worked alone.
The anonymous officials said Dzhokhar Tsarnaev and his late brother Tamerlan, seen above in a surveillance photo from right before last week's attack, were Muslim but not tied to any Islamic terrorist group.
Dzhokhar Tsarnaev was formally charged on Monday with the attack that killed three people and injured more than 200 others.
The charges include conspiring to use weapons of mass destruction against persons and property resulting in death, which carries a possible death sentence.
Tsarnaev had his first court appearance from his hospital room, where he remained in serious but stable condition.
The FBI says Tsarnaev was seen on surveillance video putting a knapsack on the ground near the site of the second blast, then manipulating a cellphone and lifting it to his ear.
Police say Tsarnaev and his older brother Tamerlan Tsarnaev, who was killed in a firefight with police, had a large cache of weapons and were probably planning more attacks.
A moment of silence was observed Monday afternoon to honor the victims, exactly one week after the explosion.
Bells also rang out across the city and state.
In a sign that Boston is getting back to normal, the FBI formally turned over control of Boylston Street, where the bombings happened, back to the Boston Police Department.
City Runners Hold Race To Honor Boston Victims
Meanwhile, close to 300 runners gathered in Central Park for an informal Monday run, to honor the victims of the Boston Marathon bombing.
The event, which originated in an online running blog, began with a moment of silence.
Boston Marathon colors were flying, and many talked about how the running community has come together in the wake of the attack, and said their minds were still with the victims.
To donate to families affected by the bombings, the mayor of Boston has set up an official fund at OneFundBoston.org.