(AP) - Attorneys for Missouri inmate Leon Taylor asked the U.S. Supreme Court to halt his execution on Tuesday, citing several concerns that led to the death sentence for the convicted killer. Taylor, 56, is scheduled to die early Wednesday for killing gas station attendant Robert Newton in suburban Kansas City in 1994, in front of Newton's 8-year-old stepdaughter. Taylor would be the ninth man put to death in Missouri this year and the 11th since November 2013. The appeal notes that Taylor's original jury deadlocked and a judge sentenced him to death. When that was thrown out, an all-white jury gave Taylor, who is black, the death sentence. In 2002, the U.S. Supreme Court ruled that only a jury could impose a death sentence. Taylor's lawyers contend that a Missouri Supreme Court ruling after the U.S. Supreme Court decision led the state to commute at least 10 other death sentences for inmates sentenced by a judge to life in prison - everyone except Taylor. Attorney Elizabeth Carlyle said Taylor essentially has been penalized for successfully appealing his first conviction. "It is difficult to imagine a more arbitrary denial of the benefit of a state court decision," Carlyle wrote in the appeal to the Supreme Court. Gov. Jay Nixon is also considering a clemency petition. In addition to the racial concerns, the petition cites abuse Taylor suffered as a child, saying his mother began giving him alcohol when he was 5 and that he later became addicted to alcohol and drugs. According to court records, Taylor, his half brother and half sister decided to rob a gas station on April 14, 1994. Newton was at the station with his stepdaughter. Taylor entered the store, drew a gun and told Newton, 53, to put $400 in a money bag. Newton complied and the half brother, Willie Owens, took the money to the car. Taylor then ordered Newton and the child to a back room. Newton pleaded for Taylor not to shoot him in front of the little girl, but Taylor shot him in the head. He tried to kill the girl but the gun jammed, so he locked her in the room and the trio drove away. "She had the gun turned on her," said Michael Hunt, an assistant Jackson County prosecutor who handled the case. It didn't fire. If it had fired, we'd have had a double-homicide. Hunt said the child's testimony at trial was pivotal in the death sentence. "You can imagine what a horrible crime this was, but when you see it coming out of a young person like that, it was hard to listen to," Hunt said. Taylor was arrested a week later after police responded to a police-tip hotline call.