Authorities in the US state of Georgia on Tuesday ended a seven-month hiatus on executions in the United States, putting to death convicted murderer William Lynd for killing his girlfriend in 1988.

Lynd (53) became the first person executed in the United States since a death row inmate was put to death in Texas on 25 September.

He was executed at 2300 GMT on Tuesday at the Jackson state prison in Georgia, a prison spokesperson said.

The hiatus followed several challenges in the US Supreme Court on the constitutionality of lethal injection, the method used to execute most death penalty inmates.

On 16 April the justices ruled 7-2 that the risk of suffering to those executed by lethal injection did not constitute "cruel and unusual punishment," which is barred under the US Constitution.

The seven justices however were split in their reasons for accepting lethal injection, all but ensuring more legal challenges to the death penalty.

The death row inmates had argued that the three-part injection method caused needless suffering in some cases.

In death by lethal injection, a first shot sedates the inmate, a second paralyses the muscles, and a third stops the heart.

If the execution goes according to plan, the inmate quickly loses consciousness and dies within a few minutes. But if the anesthesia is not properly administered, the inmate can suffer immensely.

On 23 December 1988 Lynd shot his girlfriend, Ginger Moore, in the face after an argument. He shot her a second time when she regained conscience.

Lynd put Moore into the trunk of his car and drove off, but when he heard knocking sounds he pulled over and shot her a third time. He then buried the body near an isolated farm along a highway.

According to the Death Penalty Information Center, at least 10 death row inmates are expected to be executed by the end of July, four of them in Texas, the state responsible for more than a third of all inmates executed over the past 30 years.

Nearly two-thirds of all inmates put to death in 2007 were executed in Texas, according to the Information Centre.

Lynd was the 1100 inmate executed in the United States since the Supreme Court reinstated the death penalty in 1976.

AFP