The parents of Martin Richard — the 8-year-old boy killed in the Boston Marathon bombing — are urging prosecutors to end their quest to have convicted attacker Dzhokhar Tsarnaev executed, saying that the potentially drawn-out process could prolong the anguish for victims and their families.

"We are in favor of and would support the Department of Justice in taking the death penalty off the table in exchange for the defendant spending the rest of his life in prison without any possibility of release and waiving all of his rights to appeal," Bill and Denise Richard wrote in an essay published Friday in the Boston Globe.

Bill Richard testified for the prosecution against Tsarnaev, who was convicted last week on 30 criminal counts for the bombings, which killed three people and injured 260, as well as the killing of an MIT police officer and a shootout with cops. Seventeen of the 30 counts carry the possibility of execution.

The father testified that he saw his little boy mortally wounded, his body blown apart. He recalled the shrapnel that damaged his wife's vision and maimed his daughter, Jane, who is now 9. The Richards' other son, 13-year-old Henry, was not seriously injured.

The penalty phase of the Tsarnaev trial will begin next week. Prosecutors will ask the jury to sentence him to death, while defense lawyers are expected to fight for his life, arguing that he was manipulated by his older brother, Tamerlan. Tamerlan Tsarnaev was killed in a shootout with police.

Prosecutors plan to argue that Dzhokhar Tsarnaev’s crimes meet several legal thresholds to warrant execution — including that multiple people were killed or injured, including an 8-year-old boy; that “substantial planning and premeditation” went into the crimes; and the “heinous, cruel and depraved manner” in which they were committed.

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The Richards family help unveil a banner during the two-year anniversary of the Boston Marathon bombings, on Boylston Street, in front of the former Forum Restaurant at the finish line area of the Marathon in Boston on April 15. JOHN TLUMACKI / GLOBE STAFF / EPA

The government also plans to raise additional “aggravating factors," including the “betrayal of the United States,” the selection of an “iconic event” as a target, the death of a police officer, statements in which Tsarnaev encouraged “others to commit acts of violence and terrorism,” the trauma unleashed on victims’ families, and Tsarnaev’s apparent lack of remorse.

If Tsarnaev is sentenced to death, the execution will undoubtedly be delayed by an extensive appeals process that typically lasts years.

"We know that the government has its reasons for seeking the death penalty, but the continued pursuit of that punishment could bring years of appeals and prolong reliving the most painful day of our lives," the parents wrote. "We hope our two remaining children do not have to grow up with the lingering, painful reminder of what the defendant took from them, which years of appeals would undoubtedly bring."

Justice Department officials say while the family views are an important factor, there are other law enforcement considerations — the same issues that caused the government to seek the death penalty in the first place.

Carmen Ortiz, the United States attorney for Massachusetts, responded to the essay Friday with a statement in which she said she was aware of how the Richards felt.

The family's opinion was among many that she took under consideration, Ortiz said. "I care deeply about their views and the views of the other victims and survivors," she said. "As the case moves forward we will continue to do all we can to protect and vindicate those injured and those who have passed away."

In their essay, the parents emphasized that they were not speaking for any other victims or their families. "However, it is clear that peace of mind was taken not just from us, but from all Americans. We honor those who were lost and wish continued strength for all those who were injured. We believe that now is the time to turn the page, end the anguish, and look toward a better future — for us, for Boston, and for the country."

IN-DEPTH

— Jon Schuppe, Pete Williams and Tom Winter