Jury selection begins Monday in federal court in Boston and is expected to take weeks. Judge George O'Toole Jr. refused last week to delay the trial or move it out of the city.
CNN, citing U.S. officials involved in the case, said plea negotiations failed because prosecutors were unwilling to take the death penalty off the table. Judy Clarke, representing Tsarnaev, did not respond to CNN's request for comment.
Clarke has successfully won life sentences for several notorious killers. They include Unabomber Ted Kaczynski and Jared Loughner, who killed six people and wounded U.S. Rep. Gabrielle Giffords, R-Ariz., during a public appearance by the congresswoman.
Tsarnaev, now 21, was a 19-year-old college student when he and his older brother, Tamerlan, allegedly set off two backpack bombs at the Marathon finish line on April 15, 2013, killing three people and injuring 264. Investigators said the brothers killed a Massachusetts Institute of Technology police officer on April 18, shortly before Tamerlan, 26, was killed in a confrontation with police.
Whether prosecutors will be able to find a jury willing to sentence Dzhokhar Tsarnaev to death is an open question. The Massachusetts Supreme Court ruled in 1982 that the death penalty violates the state constitution, and the state last held an execution in 1947, with governors commuting all death sentences after that.
The brothers, sons of Muslim immigrants who moved to Cambridge from Dagestan, allegedly turned to radical Islam in the months before the bombing. Tamerlan spent several months in Dagestan in southwest Russia, and Dzhokhar allegedly became more interested in religion as a student at the University of Massachusetts Dartmouth, where he was not doing well in school.
Investigators said the brothers detonated their bombs at a time when they would cause the greatest destruction when the middle-of-the-pack runners were finishing the race and their friends and families would be waiting for them.
The victims included Martin Richard, 8, whose younger sister, Jane, lost a leg. Lingzi Lu, 23, a statistics student at Boston University from Shenyang, China, and Krystle Marie Campbell, 29, a catering manager who grew up in Medford, Mass., were also killed at the finish line.
Sean Collier, 26, the MIT police officer, was about to join the Somerville, Mass., department.