Washington Gov. Jay Inslee, a Democrat, signed a bill this week officially abolishing the death penalty in the Pacific Northwest state nearly 10 years after he initiated a moratorium on capital punishment and five years after the state supreme court struck it down as "unconstitutional."

"It's official," the governor wrote on Twitter Thursday. "The death penalty is no longer in state law. In 2014 I issued a moratorium. In 2018 the state Supreme Court deemed the death penalty unconstitutional. Now in 2023, passage of SB 5087 strikes it entirely from our statutes."

Washington's supreme court ruled the death penalty was arbitrary and racially-based in 2018 after a study at the University of Washington found that juries were four times as likely to sentence a Black defendant to death than a non-Black one. 

The court converted the sentences of the eight people on Washington's death row to life in prison at the time. 

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Jay Inslee signing legislation

Washington Gov. Jay Inslee singing legislation outlawing the death penalty in the state.  (Jay Inslee/Twitter)

"The death penalty is unequally applied -- sometimes by where the crime took place, or the county of residence, or the available budgetary resources at any given point in time, or the race of the defendant," Chief Justice Mary Fairhurst wrote in the lead opinion.

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She added, "To the extent that race distinguishes the cases, it is clearly impermissible and unconstitutional." 

Defense lawyers had long challenged the death penalty on those grounds, noting the state's worst mass murderers and serial killers, Green River killer Gary Ridgway among them, had received life terms, not death. In a 5-4 ruling in 2006, the justices rejected an argument from a death row inmate that he shouldn't be executed because Ridgway hadn't been executed.

Washington’s last execution took place in 2010 when Cal Brown was given a lethal injection for the brutal rape, torture and murder of 21-year-old Holly Washa in 1991.

Fox News Digital has reached out to Inslee's office for comment. 

Empty table for lethal injections

Washington's last execution was in 2010.   (AP Photo/Jessie L. Bonner, File)

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Neighboring Idaho is one of 27 states that still allows the death penalty and is the most recent to adopt the use of a firing squad execution amid a shortage of drugs used for lethal injections and controversy around the efficacy of lethal injections. 

Mississippi, Oklahoma, Utah and South Carolina also allow firing squads and have collectively executed three condemned prisoners by that method since 1976.

The Associated Press contributed to this report.