Polis also commuted the sentences of three inmates on death row.
"Commutations are typically granted to reflect evidence of extraordinary change in the offender. That is not why I am commuting these sentences to life in prison without the possibility of parole," Polis said.
"Rather, the commutations of these despicable and guilty individuals are consistent with the abolition of the death penalty in the State of Colorado, and consistent with the recognition that the death penalty cannot be, and never has been, administered equitably in the State of Colorado," he said.
The inmates on Colorado's death row were Nathan Dunlap, who murdered four people at a children's restaurant, and Sir Mario Owens and Robert Ray, who both had been involved in the murder of a young engaged couple, Javan Marshall Fields and Vivian Wolfe. Fields was set to testify against Ray in court on charges Ray was an accomplice in a murder case.
The murders of Fields and Wolfe helped inspire Fields' mother, Aurora Democratic Sen. Rhonda Fields, to become active in public life. Fields was one of the strongest critics of the bill in 2019, objecting to the speed with which it passed through committee consideration.
She was critical in Jan. 30 debate on the bill, saying it was unjust to give all murderers the same sentence.
"We're saying that you if you kill one person, two persons, three people - it could be another Sandy Hook, it could be another club shooting, a concert shooting, a theater shooting, whatever it is - you can shoot as many people as you can, everybody gets the same penalty," she said, according to the Colorado Sun. "And the penalty is life in (prison) without the possibility of parole."
Some Republican critics of the bill wanted death penalty repeal to be put before Colorado voters in a ballot initiative.
The Colorado legislation bars the death penalty for defendants charged on or after July 1, 2020.
Pending death penalty cases and potential death penalty cases in Colorado include the case of self-confessed Planned Parenthood shooter Robert Lewis Dear, Jr. Such cases could continue.
Both Pope Francis and his immediate predecessors have condemned the practice of capital punishment in the West.
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The Colorado Catholic Conference cited the 1995 Catechism of the Catholic Church, approved by St. John Paul II. While the death penalty was considered necessary to protect society from violent criminals, under advanced prison systems the circumstances where the death penalty is necessary are "very rare, if not practically non-existent."
Pope Francis then changed the Catechism to read that the death penalty is "inadmissible because it is an attack on the inviolability and dignity of the person." He said that the Church "works with determination for its abolition worldwide."
The U.S. Conference of Catholic Bishops has voted to change the Catechism for use by adults in the U.S. to follow Pope Francis, the Colorado Catholic Conference said.
The Catholic conference also stressed the need to remember those affected by crime, saying "while today we applaud the repeal of the death penalty, we must never forget about the victims of these horrendous crimes, and as a community we must continue to support their families and loved ones," the conference said. "May they find comfort, healing and forgiveness in the love of Jesus Christ."