The Missouri Supreme Court overturned a death penalty sentence for man who is mentally retarded. Andrew Lyons, 52, was convicted of first-degree murder in 1996 and sentenced to death for the 1992 killing of his estranged girlfriend.

Lyons filed a petition in mandamus, claiming to be mentally retarded and therefore ineligible to be executed.

A court-appointed master supported Lyons' claims. The master concluded that Lyons' IQ was in a range of 61 to 70, that Lyons had continual extensive related deficits in two adaptive behaviors, and that the symptoms were present and documented before Lyons had turned 18.

"Although there is evidence, as noted earlier, that Lyons manifested these conditions before age 18, the state contends there was insufficient documentation of these conditions," the court wrote in a unanimous opinion.

"The state vigorously notes the lack of an IQ test result from prior to age 18 and the scant school records and other evidence with respect to the adaptive behaviors.