Death Row Inmate Had 15 Times Intended Dosage

An Arizona death row inmate who took nearly two hours to die during his execution was injected with 15 times the intended dosage, records show.

Joseph Wood "gasped and snorted" for more than an hour during the convicted double killer's execution on July 23.

The botched lethal injection - the third execution to go awry in the US this year - fuelled the growing debate over the death penalty and the efficacy of lethal drug cocktails.

Wood's executioners administered both a sedative and a painkiller in 50-milligramme increments 15 times, according to records released by the Arizona Department of Corrections on Friday.

Karen Sibert, an anaesthesiologist for the California Society of Anaesthesiologists, said: "Those are pretty staggering amounts of medication."

She said patients who are sedated before surgery typically receive no more than two milligrammes each of the sedative midazolam and the painkiller hydromorphone.

Wood's attorney, Dale Baich, said the newly released details show why an independent investigation is necessary.

"The Arizona execution protocol explicitly states that a prisoner will be executed using 50 milligrammes of hydromorphone and 50 milligrammes of midazolam," he said in a written statement.

"The execution logs released today by the Arizona Department of Corrections shows that the experimental drug protocol did not work as promised."

Arizona Governor Jan Brewer ordered a review of the state's execution process.

The Arizona Department of Corrections said on Friday it is seeking an outside investigator for the independent inquiry.

Wood's botched execution followed similar incidents in Ohio and Oklahoma earlier this year.

States have refused to reveal details about their lethal injection procedures, such as which pharmacies are supplying the drugs and who is administering them, because of concerns over harassment.

Corrections departments around the country are also under pressure to find sources for execution drugs after European drug companies objected to their use in capital punishment.