(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.

Internet searches

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.