Colorado Gov. Jared Polis signed a bill Monday repealing the death penalty in the state.
He also commuted the death sentences of three convicted murderers on death row, reducing their penalties to life in prison without parole.
"The commutations of these despicable and guilty individuals are consistent with the abolition of the death penalty in the State of Colorado," Polis said, "and consistent with the recognition that the death penalty cannot be, and never has been, administered equitably in the State of Colorado."
Death penalty opponents criticize the punishment as problematic for many reasons, including what they say is disproportionate application to minorities and the exoneration of some death row inmates.
Democrat and Republican lawmakers were split on the issue. Many Republican legislators pushed for the matter to be put on the 2020 ballot.
George Brauchler, Arapahoe County District Attorney, released a statement saying abolishing the penalty "should bring a smile to the faces of future serial killers, terrorists, cop killers, mass murderers, child killers, and those in prison who decide to kill again."
"We have also reduced the protections for witnesses to crime by lowering the bar for their murders," Brauchler said. "Colorado's pro-offender legislature and its current governor have signaled that those lives are worth more protection than those of their victims."
Colorado is the nation's 22nd state to abolish the death penalty. Since 1976, the state has executed only one person.