Among the most shocking allegations: Justin Ross Harris messaged six women, sending and receiving explicit texts -- some including nude images -- from work while his 22-month-old was dying, a detective testified at the hearing.
Harris' attorney repeatedly objected to Cobb County, Georgia, police Detective Phil Stoddard's testimony claiming that Harris sexted the women -- one of whom was underage at the time -- but the judge allowed it.
Police say Harris, 33, left his toddler, Cooper, strapped into a car seat under a baking sun for seven hours while he went to work June 18. Records show that the mercury topped 92 that day, and police say the temperature was 88 degrees when the boy was pronounced dead in a parking lot not far from his father's workplace.
At the hearing, Cobb County Chief Magistrate Frank Cox found probable cause for the case against Harris to move forward with respect to murder and child cruelty charges.
"For him to enter the car ... when the child had been dead and rigor mortis had set in, and the testimony is the stench in the car was overwhelming at that point in time, that he -- in spite of that -- got in the car and drove it for some distance before he took any action to check on the welfare of his child, I find there is probable cause for the two charges contained in the warrant," Cox told a packed courtroom.
The judge denied bail for Harris, who has pleaded not guilty.
In addition to the charges he faces in connection with his son's death, Harris may also be charged with felony sexual exploitation of a minor and misdemeanor illegal contact with a minor, Stoddard said.
The detective also testified about Internet searches that could raise eyebrows given the context of the case.
Before his son's death, Harris had visited a Reddit page called "child-free" and read four articles, Stoddard said. He also allegedly searched how to survive in prison.
Among the other details police have released is that Harris and his wife, Leanna Harris, told them they looked up how hot a car needed to be to kill a child.
Five days before Cooper died, Ross Harris twice viewed a sort of homemade public service announcement in which a veterinarian demonstrates on video the dangers of leaving someone or something inside a hot car.
Leanna Harris told police that she had recently seen a story on a state initiative aimed at reminding people not to leave children in cars and that it was a fear of hers, Stoddard said.
Ross Harris "stated that he recently researched, through the Internet, child deaths inside vehicles and what temperature it needs to be for that to occur," police have said, adding that Harris told investigators "he was fearful that this could happen."
During questioning, Leanna Harris "made similar statements regarding researching in car deaths and how it occurs," according to police.
The time frame for the alleged research remains unclear.
'I felt his pain; I even wept'
Thursday's probable cause hearing was expected to last 90 minutes; it stretched for some three hours.
A good chunk of that time was spent discussing how Ross Harris acted after he pulled into a shopping center asking for assistance with his son.
Witnesses told police they heard "squealing tires, and the vehicle came to a stop," Stoddard testified. Harris got out of the car yelling, "Oh, my God, what have I done?" Stoddard said.
The 33-year-old father then stood there with a blank look on his face, the detective said. When a witness told Harris his son needed CPR, Harris went to the other side of his vehicle and made a phone call, apparently to tell someone his son was dead, a witness told police, according to Stoddard.
Harris never called 911, and when an officer told him to get off his phone, he refused and even said, "F*** you" before an officer took his phone and handcuffed him, the detective said.
He also alleged that Harris told police he couldn't reach anyone on his telephone, but phone records show that Harris made three calls after he discovered his son's body, and one between him and his employer lasted six minutes, Stoddard said.
However, witness Leonard Madden offered a different version of what happened. Madden and an acquaintance were leaving a restaurant when they noticed a commotion and approached within 3 or 4 feet of a clearly distraught Harris.
"He was crying. He was hollering," Madden testified, recounting the father saying, "Oh, my God! Oh, my God, my son is dead!"
"I felt his pain; I even wept," Madden said.
According to Stoddard, Harris made statements that police felt were strange, including "I can't believe this is happening to me" and "I'll be charged with a felony."
"It was all about him," Stoddard said. "'Why am I being punished for this?' It continued. It was all very one-sided."
The detective said Harris talked about losing his job. He testified that messages between the Harrises indicate the two were having financial problems.
Ross Harris had recently been passed over for a promotion, and the couple had two insurance policies on Cooper, one for $2,000 and one for $25,000, the detective said.
Stoddard also testified about how Leanna Harris acted when she arrived at a day care enter to pick the boy up and employees there told her Cooper had never been dropped off.
"Ross must have left him in the car," she replied, according to the detective. Witnesses said they tried to tell her many other things could have happened, but Leanna Harris insisted that Ross Harris must have left the boy in the car, Stoddard said.
He also testified that when Ross and Leanna Harris were in an interview room, Ross Harris told his wife that Cooper looked "peaceful" and that his eyes were closed when he was removed from the vehicle. He told his wife, "I dreaded how he would look," Stoddard said, noting how Harris had used the past tense.
The detective added that the boy's eyes and mouth were not closed when he was taken out of the SUV.
At another point in the interview room, Stoddard said, Leanna Harris asked her husband about what he had said to police.
"She asked him -- she had him sit down, and he starts going through this. And she looks at him, and she's like, 'Well, did you say too much?' " the detective testified.
'Nothing was weird'
While prosecutors painted Ross Harris as a terrible, in fact criminal, father, the defense called witnesses who testified on his behalf.
James Alex Hall, who worked with Ross Harris and had run a Web development company with him for the past two or three months, said Harris didn't act out of the ordinary on the day his son died.
"I would say normal as you could be. Nothing stuck out. Nothing was weird," Hall said.
Ross Harris was scheduled to meet friends for a 5 p.m. showing of the movie "22 Jump Street," according to Stoddard, but he told them he'd be late. He left work at 4:16 p.m., and it would have taken him about 10 minutes to get to the theater, the detective said.
When Harris didn't show up 30 minutes into the movie, Hall stepped outside to contact him. Harris didn't respond to texts, and phone calls went straight to his voice mail, Hall said.
Asked whether Harris was a guy who talked about how life might be without a child, Hall said he was the opposite: the kind of dad who talked about his child to the point that people were tired of hearing about it.
"He said he loved his son all the time," Hall said.
On cross-examination, a prosecutor asked Hall whether he was aware of allegations that Ross Harris had been sexting various women. Hall replied no and conceded that, if that were true, he didn't know everything about his friend.
In what might be a harbinger, the defense repeatedly asked witnesses if they knew Harris was deaf in one ear, perhaps indicating that Harris might not have heard his child in the back seat when he got out of the car and when he returned to it.
"He is deaf in one ear or mostly deaf," a friend testified about Harris. "I always have to go to the other side of his head to talk to him," said Winston Rowell Milling.
'It's easy to get distracted'
Defense attorney H. Maddox Kilgore said after several witnesses testified that he didn't feel anything presented at Thursday's hearing indicated that Ross Harris intentionally left Cooper in the car, which would be key to finding him guilty on the charges.
"It's not even criminal negligence enough to support a misdemeanor," he told the judge, asking him to dismiss the warrant. "It's easy to get distracted when you get behind the wheel. Everyone does it."
Kilgore said he himself had forgotten boxed-up leftovers, a comparison on which the prosecution seized. Someone might remember that they left spaghetti in the car after 30 minutes, said Assistant District Attorney Chuck Boring.
But Harris not only forgot his child, he got an e-mail from his son's day care during the day and at one point went to the vehicle to place lightbulbs inside, never once remembering Cooper, the prosecutor said.
"I think it's remarkable he didn't stick his head in that car," Boring said. "He knew what he was going to find."
Cooper was buried Saturday in Tuscaloosa, Alabama.
The Cobb County Medical Examiner's Office determined that the child's cause of death was "consistent with hyperthermia and the investigative information suggests the manner of death is homicide," according to a Cobb County Department of Public Safety statement.
The Medical Examiner's Office is waiting for toxicology test results before making an official ruling on the toddler's death.
At the boy's funeral, Leanna Harris said she loves her husband and stands by him.
"Am I angry with Ross?" Leanna Harris told mourners. "Absolutely not. It has never crossed my mind. Ross is and was and will be, if we have more children, a wonderful father. Ross is a wonderful daddy and leader for our household. Cooper meant the world to him."