The family of an eight-year-old boy killed in the Boston Marathon bombing had urged prosecutors not to press for the death penalty against Dzhokar Tsarnaev, one of the two brothers to have orchestrated the attack.
In an essay for the Boston Globe last month, Denise and Bill Richard wrote: "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."
"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," they 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."
Bill Richard had testified for the prosecution during the trial, in which Tsarnaev was convicted on numerous criminal counts.
He told the court how he had seen his son hit and killed by the explosion, which also damaged his wife's vision and injured his daughter Jane, now nine.
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The airline apologised for the mistake.
The move will reportedly be announced in an emergency budget.
The movement was detected at 11.01pm on Saturday.