"After reviewing Georgia's death penalty statute and considering other factors, the state will not seek the death penalty in this case at this time. I cannot and will not elaborate at this juncture of the case," Reynolds said in a written statement.
Harris, who was scheduled to appear in court on Thursday, also had his arraignment postponed until October 17 because of a scheduling conflict with the defense, the statement said.
Earlier this month, the Georgia father was indicted
by a grand jury on eight counts, including malice murder and two counts of felony murder, in the June death of his 22-month-old son, Cooper.
"We're pleased with the pace and thoroughness of this investigation, which continues on today," Reynolds said at the time. "The evidence in this case has led us to this point today. Whether it leads us to anyone else remains to be answered."
He declined to take questions or comment further, saying, "This case will be tried in a court of law," and not in the media.
The lawyer for Harris' wife, Lawrence Zimmerman, said Leanna Harris is "thrilled" by the prosecutor's decision.
"He ensured us that he would only make a decision based on the evidence, not based on public opinion," Zimmerman said in a statement to reporters Wednesday. "While we are relieved with his decision, it was a calculated one."
The decision suggests that "Reynolds does not agree with the police department's first public statements that this was a case that would shock everyone's conscious," Zimmerman said.
"As far as my client is concerned, she has known from the beginning and she is thrilled with the district attorney's decision not to seek the death penalty because it affirms what we've been saying all along," he said. "This was just a tragic accident. When the truth comes out, justice will prevail for Ross."
The other five charges Harris faces are: first-degree cruelty to children, second-degree cruelty to children, criminal attempt to commit a felony (sexual exploitation of a minor) and two counts of dissemination of harmful material to minors.
The criminal attempt to commit a felony and dissemination of harmful materials charges are not related directly to Cooper's death. They involve allegations that Harris requested a nude photo of a minor's genitalia and sent the same minor descriptions of "sexual excitement and sexual conduct," according to the indictment.
A Cobb County detective testified at an earlier probable cause hearing that while Cooper was in the car at his father's workplace, Harris was sexting with numerous women and sent one of them, who was underage, a photo of his erect penis.
Harris' attorney, H. Maddox Kilgore, called the charges excessive, describing them as a part of the "state's maze of theories."
"It was always an accident. When the time comes, and we've worked through the state's maze of theories at trial, it's still going to be a terrible, gut-wrenching accident. And all the eccentricities and moral failings of Ross' life isn't going to change that," he told reporters.
According to the indictment, the grand jury found that Harris "did unlawfully, and with malice aforethought, cause the death of Cooper Harris ... by placing said Cooper Harris into a child car seat and leaving him alone in a hot motor vehicle."
Authorities have painted Harris as a terrible father who, after admittedly looking up online how hot a car needed to be to kill a child, purposely strapped his son into his sweltering SUV to die.
His motivation? The prosecutor has characterized Harris as an unfaithful husband who wanted a childless life.
Kilgore has argued his client tragically forgot his child in the car. Friends describe Harris as a doting dad, not a malicious one, who loved to show off his blond, bright-eyed boy and talked about him incessantly.
Harris left Cooper in a rear-facing car seat in the back of his 2011 Hyundai Tucson on June 18 while he spent the day at work as a Web developer for Atlanta-based Home Depot. He normally dropped the boy off at day care.
The temperature topped 92 that day -- which can make the heat inside a closed vehicle soar past 100 degrees quickly -- and police testified during Harris' probable cause hearing that Cooper spent at least seven hours in the car.