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 eventually consider the switch, which proponents say ends arguments over unnecessary suffering during injection. California and Tennessee previously considered, then rejected, the one-drug approach.

Though the untested 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 over injection say that thiopental sodium, which kills by putting people so deeply asleep 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 under 15 minutes.

Ohio inmates have typically taken about seven minutes to die after the three-drug IV injection, which combines thiopental sodium with the drugs pancuronium bromide - which paralyzes muscles - and potassium chloride, which causes cardiac arrest. Dershwitz also said in a court filing last week that a single dose of thiopental sodium would take longer than the three drugs, though he didn't specify a time.

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-killer Romell Broom. His executioners tried unsuccessfully 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 that the single-drug method should end a five-year-old lawsuit against the state that claims that injection can cause inmates severe suffering.

Lethal injection experts and defense attorneys for death row inmates have said that the one-drug method, a single dose of an anesthetic, would not cause pain.

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

All 36 death penalty states use lethal injection, and 35 rely on the three-drug method.