The Missouri Supreme Court heard arguments Thursday over whether a convicted killer's death sentence should be commuted to life without parole.

Andrew Lyons was convicted of two counts of first-degree murder and one count of involuntary manslaughter for the 1992 shotgun killings of his girlfriend, her mother, and the couple's 11-month-old son. Lyon's attorney, Frederick Duchardt, argued before the High Court that his client is, quote, "mentally retarded."

"He had to live with others throughout his life for a brief period of time; he lived by himself, and basically, as his family put it, he lives like an animal.'"

The attorney for the state, however, says that Lyons scored 84 on an IQ test before his murder trial, and that the generally-accepted score for mental retardation is 70 or lower. The State Supreme Court will issue its ruling later. © Copyright 2012, KBIA