A man convicted in 2015 in the killing of two CarQuest Auto Parts workers eight years ago in Baton Rouge is arguing he's entitled to a new trial because, he claims, a detective used improper interrogation tactics to coerce him into confessing.

The Louisiana Supreme Court last month affirmed Lee Turner Jr.'s first-degree murder convictions in the deaths of Edward "Eddie" Gurtner III and Randy Chaney but threw out his death sentence, saying the trial judge made an error during jury selection that mandated a new sentencing hearing.

Now, Turner's appellate attorneys are asking the high court to reconsider its decision upholding his convictions.

The Supreme Court concluded in its Dec. 5 ruling that Turner's confession was the product of his voluntary waiver of his constitutional rights and that statements made by East Baton Rouge Parish Sheriff's Office Detective Leo Moore during the hours-long questioning of Turner were a permissible interrogation ploy.

Turner's attorneys disagree and argue in a rehearing application filed at the high court that Turner's confession the day after the killings was the result of "coercion, duress and threats."

Turner, formerly of New Orleans, was 21 at the time of the March 27, 2011, armed robbery and shooting at CarQuest's Airline Highway store near Siegen Lane. He began working for CarQuest in Baton Rouge at a different store just 11 days before the slayings.

His attorneys complain that the detective threatened Turner with the death penalty — saying "they gonna stick a needle in your arm" — and promised to be his "lifeline" if Turner cooperated.

"This statement is a direct threat, and far more likely to incite fear and compliance in result of that fear," Capital Appeals Project lawyers Caroline Tillman and Shanita Farris, and New Orleans lawyer Timothy Yazbeck, argue in the rehearing petition.

"The (Supreme) Court ... disregarded the psychological effects of sitting through an 11-hour interrogation while being threatened with the death penalty by trained, seasoned detectives on a man in his early twenties who had never experienced a police interrogation," they add.

East Baton Rouge Parish District Attorney Hillar Moore III on Thursday said the seasoned detectives who interviewed Turner acted professionally.

"They, and all of the officers involved here, stayed within the confines of the law and their steadfast efforts ultimately led to Mr. Turner's confession to killing these two completely innocent victims," he said.

The district attorney added, as the Supreme Court noted, that Turner didn't fully confess until after being confronted with evidence found at his home and the gun he disposed of in the canal behind the CarQuest store.

A search warrant resulted in the discovery of bank bags and CarQuest deposit slips in a garbage can outside the Ritterman Avenue home where Turner was staying with an uncle.

Turner's attorneys contend he didn't confess immediately after being presented with evidence from his home.

"After realizing that the evidence was not enough to get Mr. Turner to confess, Detective Moore again turned back to the death penalty, promising to save Mr. Turner's life so his child could see him alive and be spared the pain of his father's execution," the attorneys argue.

It was only after the detective's additional references to the death penalty that Turner's will "was finally overborne," and he cried and admitted to the crime, they say.

"In actuality, the evidence presented to Mr. Turner was a straw on the heap — but the re-invoked threat of the death penalty, combined with the specter of his unborn child witnessing his execution was the straw that broke the camel's back," his attorneys maintain.

After initially denying any involvement, Turner admitted shooting Chaney, 55, of Greenwell Springs, first, then Gurtner, 43, of Denham Springs, after forcing him to open the store safe.

Gurtner, who managed the store, died with the store's keys, including one to the safe, in his hand. He was shot 12 times, including several times in the back as he tried to flee from Turner.

Chaney, who was the assistant manager of another CarQuest location but was helping out at the Airline Highway store that Sunday, was shot once in the back of the head.

Turner also told detectives he drove past the store with his pregnant girlfriend as investigators pored over the crime scene the evening of the killings.

Follow Joe Gyan Jr. on Twitter, @JoeGyanJr.