Attorneys who contend a Texas inmate set to die this week is too delusional for execution asked the U.S. Supreme Court Monday to halt his lethal injection and determine whether mentally ill people should be exempt from the death penalty because it is unconstitutionally cruel punishment.

Scott Panetti, 56, is set for lethal injection Wednesday for the 1992 shooting deaths of his in-laws at their home in Fredericksburg in the Texas Hill Country.

There was "no doubt" Panetti was severely mentally ill "before, during and after the crime for which he has been sentenced to death," his attorneys argued.

While his records have indications of mental illness, they "strongly indicate rational awareness of his impending execution and the reason for it," an assistant Texas attorney general, argued to the Fifth U.S. Circuit Court of Appeals in another appeal. - AP