(CNN) -- An Ohio inmate, convicted of killing and dismembering a 22-year-old woman in 1991, was executed Tuesday using a new, untested one-drug method of lethal injection, state officials said.
Kenneth Biros, 51, was pronounced dead at 11:47 a.m. at a prison in Lucasville, Ohio, the state attorney general's office said in a written statement.
Biros' execution is the first in Ohio since September, when the governor and federal courts halted capital punishment in the state after a botched attempt to execute another prisoner, Romell Broom. The prison staff could not find a suitable vein for the injections.
The one-drug method had never been tried on U.S. death row inmates. It relies on a single dose of sodium thiopental injected into a vein. A separate two-drug muscle injection was available as a backup, officials said. The one-drug method has been used to euthanize animals.
The same drug, sodium thiopental, at a much lower dosage, is the first ingredient in the three-drug method previously used in Ohio, as well as in all but one of the other 34 states with the death penalty. Some capital punishment opponents claim the sodium thiopental, which renders the prisoner unconscious, can wear off too quickly, and that some prisoners would actually be awake and able to feel pain as the procedure continues.
Biros was involved in litigation challenging the three-drug method, and received a stay of execution in 2007 because of his involvement in the suit, according to minutes of a November parole board meeting posted on the Ohio Department of Rehabilitation and Corrections' Web site.
His attorney, Timothy Sweeney, had also objected to the one-drug method, saying it was unconstitutional. Sweeney wrote in an appeal that use of the one-drug method would amount to "human experimentation, pure and simple."
But the 6th U.S. Circuit Court of Appeals last month denied Biros' request for a stay, concluding that since Ohio had announced it would change its protocol and rely on the one-drug method, Biros' argument regarding the three-drug method was moot. In addition, the U.S. Supreme Court without comment denied a request to stay the execution Tuesday.
Biros, 51, was convicted of killing Tami Engstrom near the town of Warren. He met the woman at a bar and offered to drive her home, and later admitted robbing and attempting to rape her. Prosecutors said Biros dismembered Engstrom and spread her body parts around northeast Ohio and neighboring Pennsylvania.
The crime was "particularly heinous, with 91 pre-mortem wounds," according to the clemency report. Biros claimed he acted in a fit of drunken rage.
During its meeting last month, members of the state parole board heard a prerecorded statement from Engstrom's mother, Mary Jane Heiss, according to the meeting minutes. Heiss said her health was not good but she was saving her strength to attend Biros' execution.
"Since her daughter's death, she has endured nearly 20 years of constant pain and nightmares," the minutes said of Heiss. "She believes that the nightmares will end with the execution. It makes her sick that Biros tortured and brutally murdered her daughter."
The board voted 7-0 to deny Biros clemency.
In attempting to execute Broom on September, authorities tried unsuccessfully for hours to find a vein to administer his lethal injection. Afterward, Gov. Ted Strickland announced he would delay the executions of two other men until March at the earliest. Broom's execution has not been rescheduled.
Ohio has put 32 people to death in the past decade, after executions resumed in the state.
--CNN's Bill Mears contributed to this report.