VARNER, Ark. (AP) — A former nurse who asked for the death sentence after smothering her two young children said, "I love you, my babies," as she was executed by injection.

Christina Marie Riggs, 28, was the fifth woman executed in the United States since the Supreme Court lifted a ban on capital punishment in 1976. It was Arkansas' first execution of a woman in more than 150 years.

Riggs had maintained throughout that she wanted to die and her last words reflected her grief.

"There is no way no words can express how sorry I am for taking the lives of my babies," she said Tuesday night. "Now I can be with my babies, as I always intended."

She had withdrawn all appeals and chose not to seek clemency from Gov. Mike Huckabee.

Riggs told authorities that she intended to use potassium chloride — the same heart-stopping drug used in executions — to kill her children, 5-year-old Justin and 2-year-old Shelby Alexis, in 1997.

She gave the children an antidepressant in hopes it would make them drowsy, then injected Justin with the potassium chloride but did not administer it properly.

When Justin began crying, Riggs told police, she injected him with morphine left over from a hospital patient and smothered both children. Riggs then took 28 antidepressant tablets, intending to commit suicide.

The children were found dead in Riggs' bed. Riggs was found on the floor.

Initially, Riggs' mother and lawyer said she suffered post-traumatic stress after working as a nurse in the aftermath of the Oklahoma City bombing. The matter was soon dropped and never came up at her trial.

Riggs worked at the Veterans Administration hospital in Oklahoma City from 1990 to July 1995, but the hospital said she was not sent to the scene of the April 1995 bombing. She later worked at the Arkansas Heart Hospital.

Prosecutors told jurors that Riggs' children had become an inconvenience to her. They said she left the children by themselves while she competed in karaoke contests and had plotted their deaths for weeks.

The last woman executed in Arkansas was Lavinia Burnett, hanged in 1845 for being an accessory to murder.

Nationally, the first woman executed since 1976 was Velma Barfield, who died by injection in North Carolina in 1984 for poisoning her boyfriend. The most recent was Betty Lou Beets, put to death in Texas in February for murdering her fifth husband.

Riggs' execution began 18 minutes late because prison workers had trouble finding a suitable vein at the 270-pound woman's elbows. She agreed to the needles at her wrists, prison spokeswoman Dina Tyler said.

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