LUCASVILLE, Ohio - Ohio executed a killer yesterday with the nation's first single-drug lethal injection, a method that is supposed to carry less risk of being painful than the conventional three-drug injection.

Kenneth Biros, 51, was pronounced dead at 11:47 a.m., 10 minutes after sodium thiopental - which kills by putting people so deeply asleep they stop breathing - began flowing into his veins at the Southern Ohio Correctional Facility in Lucasville.

The U.S. Supreme Court had rejected his final appeal two hours before.

Ohio inmates facing execution had typically taken seven minutes to die from the three-drug IV injection, still used by most death-penalty states.

The lethal cocktail combines sodium thiopental with pancuronium bromide, which paralyzes muscles, and potassium chloride, which causes cardiac arrest.

The mother, sister, and brother of Biros' victim, Tami Engstrom, applauded as the warden announced the time of death. Biros killed Engstrom, 22, in 1991 after offering to drive her home from a bar. He said he was in a drunken rage.

"Rock on," Debi Heiss, Tami's sister, said as the curtains were drawn for the coroner to check on Biros. "That was too easy."

The execution team tried for several minutes to find usable veins, including inserting needles several times in both arms, before completing the process on just his left arm after about 30 minutes.

As the chemical started flowing at 11:37 a.m., Biros' chest heaved several times and he moved his head a couple of times over about two minutes before he went still.

Ohio overhauled its procedure after a failed attempt to execute Romell Broom, a procedure halted by Gov. Ted Strickland in September.

Executioners tried for two hours to find a vein suitable for injection, hitting bone and muscle in as many as 18 needle sticks that Broom, 53, said were very painful. A hearing begins in federal court today on Broom's bid to stop the state from trying again.

The state had two goals in changing its process:

Using one drug was meant to end a five-year-old suit that claims Ohio's previous system could cause severe pain if the drugs didn't work as expected.

Lethal-injection experts and defense attorneys agreed a single dose of sodium thiopental would not cause pain.

And to avoid a repeat of the botched Broom execution, the state set up a backup procedure allowing a two-drug muscle injection.

U.S. District Judge Gregory Frost refused Monday to delay Biros' execution after Biros argued the one-drug approach was "impermissible human experimentation."

Before dying, Biros apologized for his crime. "I'm being paroled to my father in heaven," he said.