President Joe Biden heeded the calls of anti-death penalty campaigners and spared all but three federal prisoners from the threat of execution on Monday, commuting a total of 37 sentences to life in prison without the possibility of parole.

In a statement, Biden, who has overseen a moratorium on federal executions even as federal prosecutors continue to seek the death penalty, cast the move as an act of mercy. It comes after President-elect Donald Trump, during his previous term, executed 13 federal prisoners in the span of six months, more than the previous 10 presidents combined.

"Make no mistake: I condemn these murderers, grieve for the victims of their despicable acts, and ache for all the families who have suffered unimaginable and irreparable loss," Biden said in a statement explaining his decision. But he argued that taking their lives would not constitute justice.

"[G]uided by my conscience and my experience as a public defender, chairman of the Senate Judiciary Committee, Vice President, and now President, I am more convinced than ever that we must stop the use of the death penalty at the federal level," Biden said. "In good conscience, I cannot stand back and let a new administration resume executions that I halted."

Those excluded from Biden's commutations are all mass murderers: Dylann Roof, a white supremacist who killed nine Black worshipers at a South Carolina church in 2015; Robert Bowers, who killed 11 congregants at Pittsburgh's Tree of Life synagogue in 2018; and Dzhokhar Tsarnaev, who planted bombs at the Boston Marathon in 2013, killing three people.

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