Boston bombing suspect Dzhokhar Tsarnaev has arrived in a federal court in the city for his first public court appearance since the April 15 attacks.
Tsarnaev, 19, has been charged with using a weapon of mass destruction in the bombings that killed three people and wounded more than 260.
The defendant and his elder brother Tamerlan allegedly detonated two pressure cooker bombs along the closing stages of the marathon route on April 15.
A police officer was shot dead as the Tsarnaev brothers went on the run in the days following the attack.
Tamerlan was killed following a shoot-out with law enforcement officers on April 18. A seriously wounded Dzhokhar was found hiding in a boat on a suburban Boston driveway the following day.
After initially being confined at a city hospital, he was moved to a prison west of Boston.
The teenager is said to have scrawled his motives for the attacks on an interior wall of the boat.
According to court papers, he wrote: "The US government is killing our innocent civilians, we Muslims are one body, you hurt one you hurt us all.
"Now I don't like killing innocent people it is forbidden in Islam but due to said it is allowed."
If the Obama administration tries for the death penalty against Tsarnaev, it could face a long, difficult legal battle in a US state that has not seen an execution in nearly 70 years.
Massachusetts abolished its own death penalty in 1984, but Tsarnaev is being prosecuted in a federal court.
The Tsarnaev brothers had lived in the Boston area for about 10 years before launching their attacks, apparently without any assistance from an outside group.
During a recent conversation with his mother in Dagestan, Tsarnaev, a US national of Chechen origin, appeared to be in good spirits, telling her "everything was fine."
In a recording of the call obtained by Britain's Channel 4 News, Tsarnaev also said he was receiving thousands of dollars in donations from people offering support.