ATMORE, Ala. — Alabama executed convicted murderer Kenneth Eugene Smith with nitrogen gas Thursday, making it the first state to use the new method to execute a human.

Smith, 58, was declared dead at 8:25 p.m. Thursday. He appeared to convulse and shake vigorously for about four minutes after the nitrogen gas began flowing through his full-face mask in the Alabama prison's death chamber.

It was another two to three minutes before he appeared to lose consciousness, all while gasping for air to the extent that the gurney shook several times. The execution took place in the death chamber at the William C. Holman Correctional Facility in Atmore more than three decades after he was convicted of killing 45-year-old Elizabeth Sennett in a murder-for-hire scheme.

The U.S. Supreme Court refused to halt the execution in a decision delivered Thursday evening, with the court's three liberal justices dissenting. Justice Sonia Sotomayor noted Alabama's failure to execute Smith in 2022, citing concerns about the state's "hazy" protocol for its new procedure and the risk of protecting inmates from cruel and unusual punishment. "This case shows how that protection can be all too fragile," she wrote.

Thursday's execution marked the first time that a new method has been used in the United States since lethal injection, now the most commonly used method, was introduced in 1982. Here's how it played out:

7:53 p.m.

Drapes were open in the media witness room, where Smith had four witnesses. He wore a full-face mask with a plastic tube running out of a rectangular hole in the concrete block wall of the death chamber connected to the mask.

Smith was strapped to the gurney cruciform, with his arms and body secured by straps. He raised his head to look into the witness room and appeared to recognize the witnesses who were there for him.

He smiled through the mask and made the sign language sign for "I love you" and the OK sign with his left hand. He worked the fingers of his left hand as if counting.

7:55 p.m.

He was allowed to make a final statement. His words were difficult to hear, muffled by the mask.

"Tonight, Alabama caused humanity to take a step backward," he said. Smith thanked those who supported him through this process and his previous execution attempt.

"I love all of you," he said as he ended his statement. "Thank you for supporting me. I love all of you."

7:56 p.m.

The Rev. Jeff Hood, Smith's spiritual adviser, approached Smith while holding a Bible and they appeared to pray.

7:57 p.m.

A prison staff member inside the death chamber approached Smith and checked the seal of the mask. The nitrogen apparently began flowing.

7:57 to 8:01 p.m.

Smith writhed and convulsed on the gurney. He appeared to be fully conscious when the gas began to flow.

He took deep breaths, his body shaking violently with his eyes rolling in the back of his head. Hood, standing about 15 feet away, made the sign of the cross several times.

Smith clenched his fists, his legs shook under the tightly tucked-in white sheet that covered him from his neck down. He seemed to be gasping for air.

The gurney shook several times during this time. Hood removed his eyeglasses and wiped away tears.

8:02 p.m.

Smith appeared to lose consciousness. His chest remained still for about 20 seconds, and then he took several large gasps for air.

There appeared to be saliva or tears on the inside of the facemask. A female witness for Smith sobbed.

8:06 p.m.

Smith's gasping appeared to slow down.

8:07 p.m.

Smith appeared to take his last breath.

8:15 p.m.

The curtains to the witness room were closed.

In a news conference following the execution, state Department of Corrections Commissioner John Q. Hamm said Smith's reactions were "...nothing out of the ordinary."

"It appeared Smith held his breath for as long as he could, and struggled against his restraints," Hamm said. "This was expected."

Hamm said the nitrogen flowed to Smith's mask for about 15 minutes.

Five media witnesses were in the room and were taken to the prison from the media center about 4 miles away at 6:58 p.m. They remained in a trailer outside until about 7:47 p.m. when they were escorted in.

The delay was caused by difficulties in hooking up the electrocardiogram monitors to Smith, Hamm said, adding later that Smith did not struggle with prison system staff as they were attempting to attach the EKG monitors to him.

Hood and two prison system staff members stood in the death chamber, about 15 feet away from Smith. They did not wear masks.

In a change from previous executions using lethal injection as the method, a staff member did not approach Smith and check his level of consciousness when it appeared he had stopped breathing.

Alabama previously attempted to execute Smith

In 2022, Smith was strapped to the gurney to be executed by lethal injection but prison officials could not gain access to his veins before the death warrant expired and the execution process was halted.

At that time, the warrant covered 24 hours. Smith’s lawyers say he was subjected to pain and suffering as staff attempted to place the lines.

On Thursday, Smith's death warrant ran for 30 hours, from midnight until 6 a.m. Friday. That 30-hour window was put in place after the state's first unsuccessful attempt to kill Smith.

Alabama Gov. Kay Ivey confirmed the time of death in a statement about three minutes later.

"After more than 30 years and attempt after attempt to game the system, Mr. Smith has answered for his horrendous crimes," Ivey said. "The execution was lawfully carried out by nitrogen hypoxia, the method previously requested by Mr. Smith as an alternative to lethal injection."

Smith convicted for murder-for-hire plot

Smith was convicted of capital murder on Nov. 14, 1989, in the murder-for-hire plot of Elizabeth Sennett in Colbert County. She was the wife of the Rev. Charles Sennett, who hired Smith and his co-defendant to kill her in an effort to collect on her life insurance policy.

Elizabeth Sennett was stabbed to death in her home. Charles Sennett, who was in debt at the time, died by suicide a few days after her death after it became apparent that investigators suspected his involvement.

Smith’s original conviction was overturned, and he was convicted of capital murder again in 1996. His co-defendant in the case, John Forrest Parker, was executed in 2010.

Contributing: The Associated Press

Contact Montgomery Advertiser reporter Marty Roney at [email protected].