Here's an update and profile of Louis Jones, who is scheduled to be the third federal inmate executed in the past 40 years. What makes Mr. Jones' case unique is the grounds upon which he is seeking clemency: he was exposed to nerve gas as a soldier in Iraq during Gulf War I and suffered brain damage, which, his lawyers say, contributed to his crime. Jones has asked President Bush to commute his death sentence to one of life without.

Unless the Supreme Court or President Bush acts, Mr. Jones, 53, will be executed at 7 o'clock on Tuesday morning. His lawyer, Timothy Floyd, said the chemicals to which Mr. Jones was exposed in Iraq changed his personality, unbalanced his mind and played a significant role in the crimes he was convicted of committing.

Our earlier coverage of Mr. Jones' case is here. The Washington Post reported on Mr. Jones' and his clemency petition in February, and included this summary:

Jones grew up in Chicago and spent 22 years in the military before retiring in 1993 as a master sergeant in the Airborne Rangers. His honors included a meritorious service medal, a Southwest Asia service medal with three bronze service stars, a Kuwait liberation medal, badges for marksmanship and parachuting, and a good-conduct medal, according to his plea for clemency.

But, the petition says, Jones was a changed man after returning from the Gulf in May 1991.

"It solves the mystery that was at the heart of the trial: how and why someone with the background and character of Louis Jones could have committed such a horrible crime," the petition says.

Dr. Robert W. Haley, an epidemiologist and expert on Gulf War diseases at UT Southwestern Medical Center in Dallas, said in the clemency petition that Jones suffers from brain damage, not a psychological illness.

Jones and his unit were exposed to chemical fallout following U.S. bombing raids on Iraqi weapons storage sites, the petition said. He suffered from "irritability and hostility, and numerous neurological symptoms," Haley wrote.

Jones' lawyer also notes that he lacks an enzyme that would have helped his body metabolize the nerve gas.

If you'd like to express your opinion to the President, or learn more about Mr. Jones, go here.