ATMORE, Ala. — An individual sentenced for the murder of a woman over three decades ago is set to be executed on Tuesday in Alabama, marking the country’s sixth execution using nitrogen gas.

Gregory Hunt is slated for execution Tuesday night at a facility in southern Alabama. Court documents reveal that Hunt was found guilty of murdering Karen Lane, a woman he had been in a relationship with for roughly a month.

This execution in Alabama is one of four planned for this week across the nation. Florida and South Carolina also have executions scheduled. Meanwhile, an Oklahoma judge granted a temporary reprieve for an execution there on Monday, but the state’s attorney general is pushing to have the stay revoked.

Lane was 32 when she was murdered Aug. 2, 1988, in the Cordova apartment she shared with a woman who was Hunt’s cousin.

Prosecutors said Hunt broke into her apartment and killed her after sexually abusing her. A physician who performed an autopsy testified that she died from blunt force trauma and that Lane had sustained some 60 injuries, including 20 to the head.

A jury on June 19, 1990, found Hunt guilty of capital murder during sexual abuse and burglary. Jurors recommended by a vote of 11-1 that he receive a death sentence, which a judge imposed.

Hunt’s final request for a stay of execution, which he filed himself, focused on claims that prosecutors made false statements to jurors about evidence of sexual abuse. The element of sexual abuse is what elevated the crime to a death penalty offense.

In a filing to the U.S. Supreme Court, Hunt, acting as his own attorney, wrote that a prosecutor told jurors that cervical mucus was on a broomstick near Hunt’s body. However, the victim did not have a cervix because of an earlier hysterectomy. The Alabama attorney general’s office called the claim meritless and said even if the prosecutor erred in that statement, it did not throw the conviction into doubt.

Hunt, speaking by telephone last month from prison, did not dispute killing Lane but maintained he did not sexually assault her. He also described himself as someone who was changed by prison.

“Karen didn’t deserve what happened to her,” Hunt said.

Hunt said he had been drinking and doing drugs on the night of the crime and became jealous when he saw Lane in a car with another man.

“You have your come-to-Jesus moment. Of course, after the fact, you can’t believe what has happened. You can’t believe you were part of it and did it,” Hunt said.

Hunt, who was born in 1960 and came to death row in 1990, is now among the longest-serving inmates on Alabama’s death row. He said prison became his “hospital” to heal his broken mind. He said since 1988, he has been leading a Bible class attended by two dozen or more inmates.

“Just trying to be a light in a dark place, trying to tell people if I can change, they can too. … become people of love instead of hate,” he said.

Lane’s sister declined to comment when reached by telephone. The family is expected to give a written statement Tuesday night.

“The way she was killed is just devastating,” Denise Gurganus, Lane’s sister, told TV station WBRC at a 2014 vigil for crime victims. “It’s hard enough to lose a family member to death, but when it’s this gruesome.”

The Alabama attorney general’s office, in asking justices to reject Hunt’s request for a stay of execution, wrote that Hunt has now been on death row longer than Lane was alive.

Alabama last year became the first state to carry out an execution with nitrogen gas. Nitrogen has now been used in five executions — four in Alabama and one in Louisiana. The method involves using a gas mask to force an inmate to breathe pure nitrogen gas, depriving them of the oxygen needed to stay alive.

Hunt had named nitrogen as his preferred execution method. He made the selection before Alabama had developed procedures for using gas. Alabama also allows inmates to choose lethal injection or the electric chair.