19-year-old Dzhokhar Tsarnaev faces 30 charges linked to April's Boston marathon bomb blasts, which killed three people and inured 260 others.
A fourth victim, a policeman, was shot dead by him and his brother during the hunt for them, say federal prosecutors.
Seventeen charges could bring life in prison or even the death penalty, US prosecutors said.
Dzhokhar Tsarnaev's brother, 26-year-old Tamerlan, was killed in a shoot-out with police days after the twin blasts.
The explosives were described as pressure-cooker bombs, packed with shrapnel.
Dzhokhar Tsarnaev was injured in that gun battle and has been held in a prison hospital near Boston since his capture on 19 April.
The brothers are from a family of ethnic Chechen Muslims from Russia and had been living in the US for about a decade.