(CNN) -- Justin Ross Harris messaged six women, sending and receiving explicit texts -- some including nude images -- from work while his 22-month-old was dying in a hot car, a detective testified Thursday in the father's hearing on murder and child cruelty charges.
Harris' attorney repeatedly objected to Cobb County, Georgia, police Detective Phil Stoddard's testimony regarding Harris sexting the women -- one of whom was 17 -- but the judge allowed it because it was a probable cause hearing. A prosecutor insisted the testimony helped portray the defendant's state of mind and spoke to the negligence angle in the case.
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. Records show that the mercury topped 92 on June 18, 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.
Stoddard also recounted witnesses telling police Harris was acting erratically when 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," Cobb County police Detective Phil Stoddard testified. Harris exited the vehicle 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.
The detective further alleged that Harris told police he couldn't reach anyone on his telephone, but phone records show that Harris made three calls, and one between him and his employer lasted six minutes, Stoddard said.
Meanwhile, when the boy's mother, Leanna Harris, arrived at a day care center to pick the boy up, employees there told her Cooper had never been dropped off, the detective said.
"Ross must have left him in the car," she replied, according to Stoddard. Witnesses said they tried to tell her many other things could have happened, but Leanna Harris insisted that Ross Harris must have left him in the car, Stoddard said.
Dozens of reporters and spectators showed up before the hearing began. They filled the courtroom, with about 20 people left to stand.
Among those in the courtroom was the toddler's mother, who was holding another woman's hand and appeared emotional when her husband was brought into the courtroom in an orange prison jumpsuit.
At the probable cause hearing, a judge will determine whether there's enough evidence to support charges of murder and second-degree child cruelty against Ross Harris. If prosecutors are successful in making their case to the judge, it will proceed to a grand jury, where the district attorney will seek an indictment.
\It's possible but unlikely that Harris and his wife will testify, Isaza said.
Harris, who is being held without bail, has pleaded not guilty.
Accident or murder in hot-car death?
When news of the boy's death broke, it was cast as a tragic mistake by an absentminded father. Police later indicated that evidence pointed to something more sinister and that some of the father's statements to first responders "were not making sense," said Sgt. Dana Pierce of the Cobb County Police Department.
According to a criminal warrant, Ross Harris placed Cooper into a rear-facing child restraint in the backseat of his Hyundai Tucson after eating breakfast at a fast-food restaurant.
The Web developer then drove to his workplace, a Home Depot corporate office about a half-mile away, according to the warrant. Normally, Harris would drop Cooper off at an on-site day care there.
The father returned to the SUV during his lunch break, opening the driver's side door "to place an object into the vehicle," the warrant states.
Initially, police said Ross Harris had apparently forgotten that the boy was in the backseat and didn't remember until after he left work, at which point he pulled into a parking lot asking for assistance and wailing, "What have I done?"
Police had to restrain Ross Harris after it became clear Cooper had died, police said at first.
Though he didn't say exactly what led police to view the case as a crime, Pierce told CNN, "I've been in law enforcement for 34 years. What I know about this case shocks my conscience as a police officer, a father and a grandfather."
Among the details police have released is that Harris and his wife, Leanna, told them they conducted Internet searches on how hot a car needed to be to kill a child.
Death highlights key role of digital evidence
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 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," police said.
The time frame for the alleged research remains unclear.
Cooper was buried Saturday in Tuscaloosa, Alabama. At his 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."
'That pain ... never goes away'
Carol Brown, a longtime family friend who attended the funeral, said she is not ready to convict Ross Harris, as it's entirely possible he could have gone to his car during lunch and not seen the boy.
"He could have been distracted, but I do have questions about it," she said.
The Cobb County Medical Examiner's Office determined 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.
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