BOSTON — Jurors in the trial of Boston Marathon bomber Dzhokhar Tsarnaev are getting ready to hear evidence on what his punishment should be — life in prison or the death penalty — as survivors and victims’ families weigh in with their views.

The penalty phase of Tsarnaev’s trial is set to begin today in federal court.

Tsarnaev’s lawyers are expected to continue to portray Tsarnaev’s older brother, Tamerlan, as the mastermind of the 2013 deadly attack. They say Tsarnaev does not deserve the death penalty because he was a 19-year-old who was under the influence of his domineering brother.

Three people were killed and more than 260 were injured when twin pressure-cooker bombs exploded near the marathon finish line on April 15, 2013.

Tsarnaev was convicted of all 30 charges against him on April 8.

During the first phase of the trial, several people described losing legs in the bombings. Others described watching a friend or loved one die in the attack.

The penalty phase will begin just days after the parents of an 8-year-old boy killed in the bombings urged the U.S. Justice Department to take the death penalty off the table in exchange for a life sentence with no possibility of release or appeals. Jessica Kensky and Patrick Downes, a newlywed couple who each suffered severe injuries, also announced their opposition to the death penalty and said life in prison would be the best outcome to assure that Tsarnaev “disappears from our collective consciousness as soon as possible.”

Judge George O’Toole Jr. told the jury the penalty phase is expected to last about four weeks.