(CNN) The parents of the youngest victim of the Boston Marathon bombings are making an emotional, passionate plea to take the death penalty off the table for the man convicted in the case.

Last week, Dzhokhar Tsarnaev was found guilty on all 30 charges he faced related to the bombings at the 2013 race and the dramatic violence that dragged out for days afterward.

It is expected to last four weeks.

In a front-page opinion piece in The Boston Globe , Bill and Denise Richard wrote about the toll taken on their family after the death of their 8-year-old son, Martin

The Richard family before the tragedy: Mother Denise, father Bill, Martin, older brother Henry and sister Jane.

Their daughter, Jane, also was severely injured.

"Our family has grieved, buried our young son, battled injuries, and endured numerous surgeries -- all while trying to rebuild lives that will never be the same," they said in the Globe column titled "To end the anguish, drop the death penalty."

"We sat in the courtroom, day after day, bearing witness to overwhelming evidence that included graphic video and photographs, replicated bombs, and even the clothes our son wore his last day alive."

They said they understood the "heinousness and brutality of the crimes committed."

"We were there. We lived it. The defendant murdered our 8-year-old son, maimed our 7-year-old daughter, and stole part of our soul."

JUST WATCHED Survivor: I won't lose sleep over him being put to death Replay More Videos ... MUST WATCH Survivor: I won't lose sleep over him being put to death 02:47

But now the Richards are urging the Justice Department to bring the case to a close.

"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," they wrote.

They go on to say: "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. 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."

Photos: Nation mourns Boston bombing victims Photos: Nation mourns Boston bombing victims Three people were killed when two homemade explosives went off at the Boston Marathon on April 15, 2013, and a campus police officer at the Massachusetts Institute of Technology was fatally shot in the manhunt that followed. From left, the victims were Krystle Campbell, Sean Collier, Lingzi Lu and Martin Richard. Click through the gallery to see how the victims were honored and remembered in the weeks after the terror attack. Hide Caption 1 of 50 Photos: Nation mourns Boston bombing victims People pause at the memorial site in Boston's Copley Square on April 30, 2013. Hide Caption 2 of 50 Photos: Nation mourns Boston bombing victims Running shoes were among the mementos left as a tribute to the bombing victims. Hide Caption 3 of 50 Photos: Nation mourns Boston bombing victims Boston showed its resilience and heart with signs of support for the bombing victims, including this cover from an issue of Boston magazine. Hide Caption 4 of 50 Photos: Nation mourns Boston bombing victims Law enforcement officials enter St. Patrick's Church prior to Collier's funeral in Stoneham, Massachusetts, on April 23, 2013. Hide Caption 5 of 50 Photos: Nation mourns Boston bombing victims President Barack Obama observes a moment of silence in the White House Oval Office on April 22, 2013. Hide Caption 6 of 50 Photos: Nation mourns Boston bombing victims Staff members of the Beth Israel Deaconess Medical Center gather inside a trauma room to observe a moment of silence on April 22, 2013. Hide Caption 7 of 50 Photos: Nation mourns Boston bombing victims A Buddhist sits at a memorial near the marathon finish line during a moment of silence on April 22, 2013. Hide Caption 8 of 50 Photos: Nation mourns Boston bombing victims One week after the bombings, people gather to observe a moment of silence in Copley Square. Hide Caption 9 of 50 Photos: Nation mourns Boston bombing victims Officials line Boylston Street as they observe a moment of silence near the marathon finish line on April 22, 2013. Hide Caption 10 of 50 Photos: Nation mourns Boston bombing victims People take part in the moment of silence near the marathon finish line. Hide Caption 11 of 50 Photos: Nation mourns Boston bombing victims State employees pause for a moment of silence on the steps of the Massachusetts State House. Hide Caption 12 of 50 Photos: Nation mourns Boston bombing victims Pallbearers carry Campbell's casket after a funeral service in Medford, Massachusetts, on April 22, 2013. Hide Caption 13 of 50 Photos: Nation mourns Boston bombing victims Mourners walk out of St. Joseph Catholic Church after Campbell's funeral service. Hide Caption 14 of 50 Photos: Nation mourns Boston bombing victims Nurse practitioner Maureen Quaranto, who treated victims of the bombings, wears her Boston Marathon jacket during Mass on April 21, 2013. Hide Caption 15 of 50 Photos: Nation mourns Boston bombing victims From left, Boston Police Department Superintendents Kevin Buckley and William Evans attend Mass with Police Commissioner Edward Davis on April 21, 2013. Hide Caption 16 of 50 Photos: Nation mourns Boston bombing victims Photos of the deceased are displayed in Boston at the Cathedral of the Holy Cross on April 21, 2013. Hide Caption 17 of 50 Photos: Nation mourns Boston bombing victims Leaders of an interfaith service participate in a vigil near the finish line on April 21, 2013. Hide Caption 18 of 50 Photos: Nation mourns Boston bombing victims A makeshift memorial honors the bombing victims on April 21, 2013. Hide Caption 19 of 50 Photos: Nation mourns Boston bombing victims Nicole Collier Lynch, Collier's sister, hugs a police officer during a vigil in Wilmington, Massachusetts, on April 20, 2013. Hide Caption 20 of 50 Photos: Nation mourns Boston bombing victims People gather at a makeshift memorial in Boston on April 20, 2013. Hide Caption 21 of 50 Photos: Nation mourns Boston bombing victims Huntsville, Alabama, residents hold a prayer vigil on April 19, 2013. Hide Caption 22 of 50 Photos: Nation mourns Boston bombing victims A man rings a bell at the vigil in Huntsville. Hide Caption 23 of 50 Photos: Nation mourns Boston bombing victims Two women embrace during a candlelight vigil in Somerville, Massachusetts, on April 18, 2013. Hide Caption 24 of 50 Photos: Nation mourns Boston bombing victims Obama talks with staff members at Massachusetts General Hospital while visiting injured patients on April 18, 2013. Hide Caption 25 of 50 Photos: Nation mourns Boston bombing victims A man at a Boston restaurant watches Obama speak on television on April 18, 2013. Hide Caption 26 of 50 Photos: Nation mourns Boston bombing victims Mourners fill a Boston cathedral for an interfaith service on April 18, 2013. Hide Caption 27 of 50 Photos: Nation mourns Boston bombing victims Obama, first lady Michelle Obama and Massachusetts Gov. Deval Patrick attend the interfaith prayer service. Hide Caption 28 of 50 Photos: Nation mourns Boston bombing victims Flowers, running shoes and other items are left in memory of bombing victim Lingzi Lu. Hide Caption 29 of 50 Photos: Nation mourns Boston bombing victims Dennis Seidenberg of the Boston Bruins observes a moment of silence before the start of an NHL hockey game in Boston on April 17, 2013. It was the first sporting event held in the city after the bombings. Hide Caption 30 of 50 Photos: Nation mourns Boston bombing victims Danielle Cerroni writes a chalk message on the street near the marathon's finish line on April 17, 2013. Hide Caption 31 of 50 Photos: Nation mourns Boston bombing victims A woman looks at memorials left at the scene of the attack. Hide Caption 32 of 50 Photos: Nation mourns Boston bombing victims A crowd gathers at Boston's Garvey Park during a vigil for bombing victim Martin Richard on April 16, 2013. Hide Caption 33 of 50 Photos: Nation mourns Boston bombing victims A woman uses her hand to keep wind from her candle during an interfaith service in Boston on April 16, 2013. Hide Caption 34 of 50 Photos: Nation mourns Boston bombing victims Mourners gather on the edge of the pond for a candlelight vigil in Boston on April 16, 2013. Hide Caption 35 of 50 Photos: Nation mourns Boston bombing victims Students from the Clifden Academy hold an American flag and candles during a vigil in Dorcester, Massachusetts, on April 16, 2013. Hide Caption 36 of 50 Photos: Nation mourns Boston bombing victims People walk along the barricade at Boylston Street on April 16, 2013. Hide Caption 37 of 50 Photos: Nation mourns Boston bombing victims Mourners in Boston hug one another during a vigil for victims on April 16, 2013. Hide Caption 38 of 50 Photos: Nation mourns Boston bombing victims Five-time Boston Marathon runner Jose Sotolongo, center, reacts during a moment of silence in Miami on April 16, 2013. Hide Caption 39 of 50 Photos: Nation mourns Boston bombing victims The New York Islanders and Florida Panthers stand for a moment of silence before an NHL hocky game in Uniondale, New York, on April 16, 2013. Hide Caption 40 of 50 Photos: Nation mourns Boston bombing victims Members of the Boston Red Sox observe a moment of silence before their Major League Baseball game in Cleveland on April 16, 2013. Hide Caption 41 of 50 Photos: Nation mourns Boston bombing victims From left, Boston Marathon runners Tammy Snyder, Diane Deigmann and Lisa Kresky-Griffin embrace at the barricaded entrance to Boylston Street on April 16, 2013. Hide Caption 42 of 50 Photos: Nation mourns Boston bombing victims Two young girls leave flowers on the steps outside the Boston home of 8-year-old bombing victim Martin Richard on April 16, 2013. Hide Caption 43 of 50 Photos: Nation mourns Boston bombing victims Traders at the New York Stock Exchange observe a moment of silence before the opening bell on April 16, 2013. Hide Caption 44 of 50 Photos: Nation mourns Boston bombing victims The flag above the White House flies at half-staff on April 16, 2013. Hide Caption 45 of 50 Photos: Nation mourns Boston bombing victims The Minnesota Twins stand during the national anthem before a baseball game in Minneapolis on April 15, 2013. Hide Caption 46 of 50 Photos: Nation mourns Boston bombing victims Obama makes a statement about the bombings on April 15, 2013. Hide Caption 47 of 50 Photos: Nation mourns Boston bombing victims Players and fans observe a moment of silence before an NBA game in Oakland, California, on Aprl 15, 2013. Hide Caption 48 of 50 Photos: Nation mourns Boston bombing victims An American flag flies at half-staff at the Capitol building in Washington on April 15, 2013. Hide Caption 49 of 50 Photos: Nation mourns Boston bombing victims Hockey fans in Glendale, Arizona, pause for a moment of silence before a game on April 15, 2013. Hide Caption 50 of 50

Martin Richard and two others were killed and more 200 people wounded when a pair of bombs went off within 12 seconds of each other at the finish line on April 15, 2013.

Tsarnaev was convicted last week, while his brother, Tamerlan, was killed in a shootout with police two years ago.

The Richards never mention Tsarnaev by name. They stress that they were only speaking for themselves when they argue against the death penalty.

"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," they wrote.