WASHINGTON ? Ohio became the first state Tuesday to execute a convicted murderer with just one drug in a new procedure that has raised a host of legal and ethical questions over lethal injection and capital punishment.

Kenneth Biros, sentenced to death for killing and dismembering a 22-year-old woman in 1991, was pronounced "dead at 11:47 a.m., nine minutes after the injection started," said Julie Walburn, spokeswoman for the Ohio Department of Rehabilitation and Correction.

Biros was given a lethal dose of an anesthetic, replacing the three-drug cocktail used in executions in 34 of the 35 other US states where capital punishment is practiced.

The novel method has garnered support from some, who claim it is a less painful, more humane way to carry out executions.

Ohio prisons director Terry Collins was quoted by the local Columbus Dispatch newspaper as saying there were "no problems whatsoever" with the new method.

"The process worked as expected," he said.

The US Supreme Court refused to intervene at the last minute, delaying the execution by an hour while it considered and rejected the final appeal.

But it may still be asked to consider the constitutionality of the new procedure, which could become standard practice for executions.

Biros' unsuccessful appeal for a stay of execution argued that the unknown consequences of the new method made the protocol a violation of the constitutional prohibition on "cruel and unusual punishment."

Family members of Biros' victim, Tami Engstrom, celebrated the execution, though her sister Debi Heiss complained to the Dispatch that the punishment was "too smooth."

"I think he should have gone through some pain for what he did," she said.

Critics argued that Biros, 51, was a human guinea pig being subjected to an untested procedure and his lawyer even described the process as "human experimentation."

Ohio switched to the new method after a disastrous attempt in September to execute another inmate, Romell Broom.

Executioners spent two hours searching for a vein to inject Broom -- convicted of the rape and murder of a 14-year-old girl -- failing 18 times to insert a needle before giving up.

In Biros' case, and using the new procedure, it took 30 minutes to find an appropriate vein for the injection, according to local media reports.

All executions in Ohio were put on hold after Broom's failed execution, as the state searched for an alternative to the old method, which uses one drug to anesthetize, another to paralyze and a third to stop the heart.

The new method uses only the anesthetic drug -- thiopental sodium -- but in a dose two-and-a-half times greater than the amount usually administered, similar to methods used to euthanize animals.

The new protocol also includes a back-up option that means executioners can deliver an intramuscular injection containing massive doses of two chemicals, a sedative and a painkiller, if they cannot find a vein.

The process can be repeated three times until the prisoner is dead.

Biros was originally to be executed in March 2007, but the US Supreme Court put his execution on hold at the eleventh-hour because of a federal suit challenging the three-drug lethal injection procedure.

The US Supreme Court upheld the constitutionality of the lethal injection in a landmark 2008 ruling.

Tuesday's execution was the 51st US execution in 2009, and the fourth and final scheduled for this year in Ohio.