This undated photo provided by the Georgia Department of Corrections on Wednesday, Oct. 12. 2016, shows death row inmate Gregory Paul Lawler. Convicted of killing an Atlanta Police Officer John Sowa in 1997, he is scheduled to be executed in Oct. 19, 2016, according to Attorney General Sam Olens. (Georgia Department of Corrections via AP)

ATLANTA - A Georgia prisoner who was recently diagnosed with autism should not be put to death, his lawyers argue in court briefs, saying his scheduled execution this week would be unconstitutional.

Gregory Paul Lawler, 63, is scheduled to die Wednesday by injection of the barbiturate pentobarbital at the state prison in Jackson. He was convicted of murder in the October 1997 shooting death of Atlanta police Officer John Sowa and also critically injured Officer Patricia Cocciolone.

Lawler's attorneys on Monday asked a judge in Fulton County Superior Court, where he was originally convicted, to halt his execution and grant an emergency request for a new trial. They said the court cannot be confident Lawler would receive a death sentence if jurors were aware that he suffered from autism spectrum disorder.

In a separate court filing in Butts County, where Georgia's death row is located, his lawyers challenged the constitutionality of executing him. The death penalty "no longer comports with the evolving standards of decency in this State or in the country at large," his lawyers argued. They added that Lawler is ineligible for execution because his autism spectrum disorder "leaves him with diminished capacities that reduce his culpability in a manner akin to intellectually disabled and juvenile offenders" whose execution is barred by law.

His lawyers also cited his recent diagnosis in a clemency application to the State Board of Pardons and Paroles. The board held a clemency hearing Tuesday before denying Lawler's request. Following its standard practice, the board didn't give a reason for its denial of clemency. It's the only authority in Georgia that can commute a death sentence.

A clinical neuropsychologist last month diagnosed Lawler with autism spectrum disorder with symptoms that most closely match those of Asperger's syndrome, his lawyers said.

The disorder has distorted every social interaction in Lawler's life, isolated him from those around him and had a profound and tragic effect on his interaction with Sowa and Cocciolone, his lawyers said. The officers likely didn't understand some of the decisions he made that night, and he misinterpreted the intentions of the officers and felt that he needed to fight for his life, his lawyers said.

Sowa and Cocciolone were responding to a report of a man hitting a woman the evening of Oct. 12, 1997, and arrived at a parking lot to find Lawler trying to pull his drunk girlfriend to her feet. Lawler quickly left and returned to his nearby town house, and the officers decided to help his drunk girlfriend get home.

When they knocked on the door, Lawler cursed, yelled and told the officers to leave. Once his girlfriend was inside, he tried to shut the door on them. Sowa put his hand up to keep the door from shutting and said they just wanted to make sure the girlfriend lived there and that she would be safe.

Lawler grabbed an AR-15 rifle and fired 15 times as the officers fled, using bullets that can penetrate body armour, prosecutors said.

When other officers responded to Cocciolone's radio distress call, they found Sowa lying near the sidewalk and Cocciolone on the ground in the front yard. Both officers' pistols were still in their holsters.

The responding officers got Lawler's girlfriend out of the apartment, and Lawler finally surrendered after a six-hour standoff.

Lawler's execution would be the seventh in Georgia this year, the most in a calendar year in the state since the death penalty was reinstated nationwide in 1976. Georgia executed five inmates last year and in 1987.

News from © The Associated Press, 2016