A convicted killer who would have been the 1,000th American executed since the death penalty was reinstated in 1976 was granted clemency this week, just hours before he was scheduled to die. Robin Lovitt, 42, was convicted of stabbing a man to death with a pair of scissors during a 1998 pool hall robbery. Lovitt admits he participated in the robbery, but claims he was in the bathroom when the killing took place. His lawyers have argued that DNA tests on the scissors could prove his innocence. But authorities disposed of the scissors after Lovitt was convicteda factor cited by Democratic Virginia Gov. Mark Warner when he commuted Lovitts sentence from death to life in prison. I believe clemency should only be exercised in the most extraordinary circumstances, Warner said. The improper discarding of evidence by prosecutors, he said, was such a circumstance.