The case so far has been an emotional one, with the defense saying Harris was a loving father who experienced a tragic -- but not unheard of -- breach of memory. The prosecution, on the other hand, says Harris knew his son was in the car, and may have had personal reasons for wanting the boy out of his life.
While the case centers on Cooper's death, prosecutors plan to introduce evidence to support allegations that the churchgoing 35-year-old regularly sought sexual fulfillment outside his marriage and maintained a sordid online presence.
The trial was supposed to begin earlier this year. But Cobb County Judge Mary Staley agreed to move the trial
from her court in metro Atlanta because Harris' attorneys made a "substantive showing" that extensive publicity had potentially prejudiced jurors.
Harris' trial has since moved about 300 miles southeast to the coastal city of Brunswick, Georgia. After jury selection resumed last month, the pool was narrowed Monday down to 12 jurors and four alternates. Opening statements are set to begin Monday afternoon. The trial is expected to last at least a month.
Here's an overview of the case.
The death of Cooper Harris
On June 18, 2014, Justin Ross Harris, then 33, strapped his son Cooper into his rear-facing carseat in the back seat of the car. Harris then drove the pair from their Marietta, Georgia, home to a nearby Chick-fil-A. Afterward, instead of dropping Cooper off at his day care, which was minutes from the restaurant, Harris continued to The Home Depot corporate headquarters where he worked. At 9:25 a.m. Harris arrived at work, leaving Cooper strapped in his car seat.
Later that morning Harris and some co-workers left the corporate campus to go to lunch. Upon returning at approximately 12:45 that afternoon, Harris went to his car and opened the door to put away some light bulbs he had bought during his lunch break. The defense says Harris did not notice his son, still in the backseat. According to medical examiners, Cooper was likely already dead.
Sometime after 4 p.m., when Harris was driving toward a theater where he was supposed to see a movie, Harris says he noticed his son.
Harris pulled into a shopping center parking lot roughly seven minutes after leaving the Home Depot campus. He pulled Cooper's lifeless body from the car. His screams attracted a crowd of onlookers, some of whom called 911 and others of whom attempted to help Harris administer first aid to Cooper.
Witnesses said Harris was hyperventilating and screaming. Cobb County police Detective Phillip Stoddard testified that Harris swore at police when they arrived at the scene. Harris attempted to call his then-wife and Cooper's mother, Leanna Harris, but he did not get an answer.
Meanwhile, Leanna Harris was already headed to the day care where her husband had agreed to drop off Cooper. When she learned Cooper had never arrived, witnesses said she came to an immediate conclusion.
"Ross must have left him in the car," she's reported as saying
. "There's no other explanation. Ross must have left him in the car."
At 10 p.m., Justin Ross Harris was arrested. An autopsy later confirmed that Cooper Harris died of hyperthermia.
Suspicions and indictment
Every year, there are dozens of recorded cases
of parents accidentally leaving their children in the back of cars. At first, news of Cooper's death seemed to be part of this phenomenon.
However, in September 2014, a grand jury returned an eight-count indictment against Justin Ross Harris. The charges included malice murder, two counts of felony murder and cruelty to children in the first degree.
Some of the charges in Harris' indictment stemmed not from Cooper's death, but from Harris' alleged habit of sending sexual text messages to underage girls. According to prosecutors, Harris was having these illicit chats with as many as six women on the day his son died.
Investigators found Harris made online searches
in the days before Cooper's death related directly to babies in hot cars, and one search for "how to survive prison."
When Harris was being held at the police precinct the day of Cooper's death, Detective Stoddard said he seemed preoccupied with his own fate.
"It was all about him: 'I can't believe this is happening to me. Why am I being punished for this?'"
Stoddard also said Leanna Harris asked her husband, "Did you say too much?"
Investigators for the prosecution questioned details of the incident. They conducted tests
that showed Harris could have seen Cooper in the back seat of the car from his position in the front seat. They also discovered Harris received a group email
that day from Cooper's day care that apparently failed to jog his memory.
Upon signing off on the indictment, Cobb County Chief Magistrate Frank Cox also remarked
that Harris should have noticed that "the stench in the car was overwhelming" upon entering the car that afternoon.
Infidelity and online activity
Strange internet searches weren't the only remarkable things about Justin Ross Harris' online life. An investigation into his Internet habits found Harris was active on several dating sites, as well as messaging apps like Kik and Whisper.
On Whisper, an app that encourages people to tell secrets, Stoddard testified that Harris wrote
"I miss having time to myself" and said he hated being married with kids. Harris also visited a "child-free" message board
The prosecution also alleged Harris met with prostitutes and other women in the days before his son died. The assistant district attorney in the case said Harris' sexual behavior interrupted time he spent with Cooper
, citing a time when Harris allegedly sent pictures of his genitalia to women while attending an Atlanta Braves baseball game with his son.
Divorce and second indictment
Evidence showed Leanna Harris had prior knowledge of her husband's infidelity. She filed for divorce in February 2016
, saying "the marriage is irretrievably broken."
In March 2016, the Cobb County district attorney indicted Harris
on eight additional counts related to his sexual activity with minors, including two counts of sexual exploitation of minors.
What happens next?
Upon Judge Staley's ruling about the change of venue, Cobb District Attorney Vic Reynolds said his team was disappointed but that the state would be ready "whenever and wherever this case is set for trial."
On September 12, both the prosecution and defense resumed jury selection at the Glynn County Courthouse in Brunswick, Georgia. The pool, which consisted of 280 potential jurors, has been narrowed down and the trial is set to begin.
If Harris is convicted of murder, he faces life in prison. The prosecution has chosen not to seek the death penalty.