Jury selection began on January 5 in the U.S. trial of Dzhokhar Tsarnaev, the surviving suspect in bombings that killed three people and wounded 264 at the Boston Marathon in 2013.
Tsarnaev, who could face the death penalty if convicted, appeared in federal court in Boston opposite an initial group of 200 to 250 potential jurors.
U.S. District Judge George O'Toole briefly went over the charges against him.
The selection process is expected to last weeks as a jury is picked from a pool of about 1,200 people.
The 12 jurors will then have to decide if the 21-year-old Tsarnaev, a naturalized U.S. citizen with roots in Russia's North Caucasus, is guilty of planning and carrying out the bombings.
Another murder charge has been filed in the death of a security guard who was shot after the bombings.
Prosecutors contend that Tsarnaev and his older brother, Tamerlan, were responsible for the bombings.
Tamerlan was killed in a shootout with Boston police.