COLUMBUS, Ohio - Condemned killer Kenneth Biros could become the first person in the country put to death with a single dose of an intravenous anesthetic instead of the usual - and faster-acting - three-drug process if his execution proceeds tomorrow.

The execution could propel other states to consider the switch, which proponents say should end arguments over unnecessary suffering during the injection, though California and Tennessee have considered and rejected the one-drug approach.

Though the method has never been used on an inmate in the United States, one difference is clear: Biros will likely die more slowly than inmates put to death with the three-drug method, which includes a drug that stops the heart.

Lethal-injection experts on both sides of the debate say thiopental sodium, which kills by putting people so deeply asleep that they stop breathing, will take longer.

How much longer is unclear: Mark Dershwitz, an anesthesiologist who advised Ohio on its switch to the single drug, has written that death should occur in less than 15 minutes.

Ohio inmates have typically taken seven minutes to die after the three-drug injection, which combines thiopental sodium with pancuronium bromide, which paralyzes muscles; and potassium chloride, which causes cardiac arrest.

The switch from three drugs to one was ordered last month because of the state's botched attempt on Sept. 15 to execute convicted rapist and killer Romell Broom.

Broom's executioners tried for two hours to find a usable vein for injection, painfully hitting bone and muscle in as many as 18 needle sticks. Gov. Ted Strickland halted the execution.

Broom, 53, has appealed the state's attempt to try again.

Ohio officials contend the single-drug method should end a five-year-old lawsuit against the state that claims injection can cause severe suffering.

Lethal-injection experts and attorneys for death-row inmates have said the single dose of anesthetic would not cause pain.

Biros, 51, killed 22-year-old Tami Engstrom near Warren, Ohio, in 1991 after offering to drive her home from a bar, then scattered her body parts in Ohio and Pennsylvania.

All 36 states that have the death penalty use lethal injection, and 35 rely on the three-drug method. Nebraska, which recently adopted injection over electrocution, has proposed to use the three-drug method but hasn't made the decision final.

States with death chambers will likely watch Ohio's experience and the court challenges before deciding, said Richard Dieter, executive director of the Death Penalty Information Center.

The U.S. Supreme Court said last year that states would have to change the three-drug process only if an alternative method lessened the possibility of pain. Defense attorneys have also supported the one-drug option, reducing the possibility of legal challenges, Dieter said.

Biros' attorneys want his execution delayed, saying the new, untested method had never been used in "any other civilized country" and would amount to human experimentation. But they earlier advocated for the state to switch to the one-drug method.