McALESTER, Okla. (AP) — Oklahoma executed a 36-year-old man on Tuesday for taking part in the brutal killing of a ranching couple 13 years ago.

James Lewis DeRosa was killed by lethal injection at the Oklahoma State Penitentiary in McAlester, becoming the state’s second inmate executed this year.

At a clemency hearing last month, DeRosa took responsibility for his role in the Oct. 2, 2000, stabbing deaths of Curtis and Gloria Plummer, for whom he had previously done some ranch work. He also apologized to their family.

Strapped to the gurney in the penitentiary’s death chamber, though, he had nothing to say before the fatal mixture of drugs was pumped into his veins.

“Mr. DeRosa, would you like to make a last statement?” Warden Anita Trammell asked.

“No, ma’am,” DeRosa replied.

DeRosa took three heavy breaths before his face turned ashen and he stopped breathing.

According to prosecutors, DeRosa had worked on the Plummers’ ranch in the Le Flore County community of Poteau, and on the day of the killings, he and accomplice John Eric Castleberry went there under the pretense of looking for work.

DeRosa and Castleberry persuaded the couple to let them into their home and then attacked them, stabbing the couple over and over and slashing both their necks, prosecutors said. They made off with $73 and the couple’s pickup truck, which was found abandoned at a nearby lake.

Castleberry, 33, testified against DeRosa as part of a deal with prosecutors in which he received a sentence of life in prison without the possibility of parole.

At his clemency hearing before the Oklahoma Pardon and Parole Board last month, DeRosa spoke via a video link from prison about how he had found religion and turned his life around behind bars. He urged the board to recommend to Gov. Mary Fallin that she commute his sentence to life in prison so that he could be a positive influence on his fellow inmates. He also apologized to the victims’ loved ones and owned up to what he had done.

“I can’t express how truly sorry I am for the pain I’ve caused the Plummer family,” DeRosa said. “I take full responsibility for their deaths. If not for me, they wouldn’t have died that night.”

The family wasn’t swayed, and the board voted 3-2 to not recommend he be pulled off of death row.

After the execution, the Plummers’ daughter, Janet Tolbert, said the execution wasn’t about DeRosa.

“This is about Curtis and Gloria Plummer. The family of Curtis and Gloria are pleased that justice has been served,” said Tolbert, who was wearing a T-shirt emblazoned with a picture of her parents’ faces.

Tolbert said she wasn’t surprised that DeRosa didn’t express remorse in the death chamber, because she said he didn’t do so in court. She said the clinical and peaceful way DeRosa died belies the horrifically violent manner in which her parents were killed.

“It was horrible,” she said. “They suffered a horrendous death. They missed out on so much.”

In a letter to the parole board, Tolbert wrote that she still has nightmares about finding her parents dead.

“I saw my 70- and 73-year-old parents laying in pools of blood that went through the carpet to the cement foundation, with both of their throats slashed from ear-to-ear and stab wounds all over their 70-year-old bodies,” Tolbert said.

DeRosa was the second Oklahoma inmate executed this year. Another inmate, 39-year-old Brian Darrell Davis, is scheduled to die next Tuesday, after Fallin rejected the parole board’s recommendation to commute his sentence to life. Another inmate, Anthony Rozelle Banks, 60, is slated for execution in September.