(CNN) -- A judge will determine this week whether there's enough evidence to keep in jail a Georgia man whose son died in a hot SUV.
Justin Ross Harris, who is charged with murder and second-degree child cruelty, will go before a judge Thursday for a probable cause hearing.
Police say Harris left his 22-month-old son, Cooper, strapped into a car seat under a baking sun for seven hours while he went to work.
The boy died, and Harris sits in jail without bail. He has pleaded not guilty.
At a probable cause hearing, the prosecution tries to convince the judge that a crime has been committed and the defendant committed it.
Among the tidbits police have released about the case is that Harris and his wife, Leanna, told them that they conducted Internet searches on how hot a car needed to get to kill a child.
"During an interview with Justin, he 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. "Justin stated that 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 when this alleged research took place remains unclear.
Wife stands by Harris
Cooper, who died June 18, 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 a crowd at the funeral. "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."
Harris calls in
Though Harris wasn't allowed out of the Cobb County Jail to attend the funeral, he called in and spoke to the entire auditorium on speakerphone.
"Thank you for everything you've done for my boy," he said. "Good life. (Inaudible) No words to say. Just horrible. (Inaudible) I'm just sorry I can't be there." "
He told everyone he loved them and started crying again.
Carol Brown, a longtime family friend, was one of those in attendance.
"I mean he could have gone to the car and not seen the little boy, if the boy was sleeping, or you know ... it could happen," she said.
"He could have been distracted. But I do have questions about it."
Timeline of events
Initially, police described the death of the toddler as the result of tragic absent-mindedness.
They said the dad had apparently forgotten the boy was in the back seat of his Hyundai Tucson; he didn't remember until he was done with his workday, drove a couple of miles and pulled into a shopping center parking lot.
But suspicions grew as police investigated.
On the day Cooper died, his father stopped for breakfast at a fast-food restaurant and afterward strapped his son into a rear-facing child restraint seat on his SUV's back seat, police said.
He drove to his workplace, a Home Depot corporate office, about a half-mile away. He works as a Web designer there.
Usually, he would take his son to an on-site day care. But that day, police said, Harris left him in the car seat.
During his lunch break, he returned to his car, opening the driver's side door to put something inside, police said.
After work, around 4:16 p.m., the 33-year-old father got in his car and drove away. A few miles away, he stopped the car at a shopping center and called for help.
When it became clear Cooper was dead, Harris was so inconsolable police had to restrain him.
"What have I done?" he wailed as he tried to resuscitate the boy.
The Cobb County medical examiner's office found the child's cause of death "consistent with hyperthermia and the investigative information suggests the manner of death is homicide," according to a Cobb County Department of Public Safety statement issued last week. Temperatures hit 92 degrees Fahrenheit on the day of Cooper's death.
The medical examiner's office is waiting for toxicology test results before making an official ruling as to the cause and manner of the toddler's death.
CNN's Vivian Kuo, Marlena Baldacci and Nick Valencia contributed to this report.