OKLAHOMA CITY — The sentences of more than 500 prisoners were reduced Friday by the Oklahoma Pardon and Parole Board, setting the stage for their release within days.

The commutation orders were issued under a new state law allowing the board to review sentences of inmates in prison for crimes no longer considered felonies.

The board said it was the largest single day commutation of prisoners in U.S. history.

Gov. Kevin Stitt, who is required to approve the commutations, praised the board action. His office said he would begin processing them immediately.

That means 462 of the 527 inmates will be released Monday. Sixty-five others have legal detainers that must be disposed of before they are set free.

Commutations reduce prison sentences but do not erase inmate convictions from public records. The state expects the new law to save $11.9 million in prisoner custody costs this year.

“This is a historical day for criminal justice reform in Oklahoma,” said a statement from Steven Bickley, executive director of the Pardon and Parole Board. “With this vote, we are fulfilling the will of Oklahomans.

Bickley said the goal of the commutation program was to release low level, non-violent offenders and provide for “the successful reentry of these individuals back into society.”

He said the board considered 814 inmates for commutation during a special meeting on the first day the new justice reform law took effect. He said the board will continue to review other low-level offenders. The governor said he expects 2,000 inmates to go free by year’s end.

In 2016, Oklahomans voted to reclassify certain nonviolent drug and theft crimes from felonies to misdemeanors in an effort to reduce the state’s incarceration levels and related costs.

Then earlier this year, the state Legislature passed a bill implementing the changes, making simple drug possession a misdemeanor and boosting the threshold for felony property charges from $500 to $1,000.

Male prisoners comprised 75 percent of the commutations. The average age of prisoners set for released is 40. They were imprisoned for three years.

To prepare for their release, prison officials deployed scores of volunteers to help with job fairs,  process paper work to re-issue or return driver’s licenses and state-issued IDs, and  set up special programs to help the prisoners successfully re-enter society.

 “This was a huge first step in the right direction for criminal justice reform,” said state Rep. Jason Dunnington, D-Oklahoma City, co-author of the new law. “And folks, believe me, we have a lot more to do.”

CNHI’s Oklahoma State Reporter Janelle Stecklein contributed details to this story.