Alexandria, Va. ? The Virginia Supreme Court on Thursday ordered a new trial to determine whether a death row inmate is mentally retarded and therefore ineligible for capital punishment.

The inmate, Daryl Atkins, was at the heart of the landmark U.S. Supreme Court ruling in 2002 that executing the retarded is unconstitutional.

The high court left it to the states to define retardation and sent Atkins’ case back to circuit court.

Last August, a Virginia jury determined Atkins was not retarded, allowing his death sentence for a 1996 murder to stand.

The state Supreme Court ordered the new trial on Atkins’ mental status Thursday because the jury had been improperly told Atkins had previously been sentenced to death.

Atkins was convicted in the robbery and shooting death of Air Force enlisted man Eric Nesbitt, who was abducted outside a convenience store, forced to withdraw money from an ATM and driven to a desolate road, where he was shot. Atkins was 18 at the time.