Story highlights Justin Ross Harris called in to his son's funeral in Tuscaloosa, Alabama

Search warrant says he told police he researched child deaths inside vehicles

Harris has pleaded not guilty to murder and child cruelty charges

Harris is being held without bond in jail

The suspect in a Georgia toddler's death told police he used the Internet to research child deaths inside vehicles, a search warrant said.

The father, Justin Ross Harris , 33, has pleaded not guilty to charges of murder and second-degree child cruelty in the death of his 22-month-old son, Cooper Harris. The boy died after he was left seven hours in a sweltering SUV on June 18.

"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," according to a sworn statement in the warrant from a police officer. "Justin stated that he was fearful that this could happen."

According to search warrants from a Cobb County magistrate court, investigators seized a number of items from the father's home: An iPhone 5, Hyundai car, home laptop computer, computer tower, a "Google chrome cast Internet searcher" and other electronic devices.

Cobb County Police said the purpose of the search warrants was to find blood, DNA, writings and photographs relating to child abuse, child neglect, homicide to children and cruelty to children.

Justin Ross Harris has pleaded not guilty to charges of murder and second-degree child cruelty in the death of his 22-month-old son.

Harris sits in jail without bond, with an appearance before a judge set for next Thursday. Police in Cobb County, part of metro Atlanta, have been tight-lipped and haven't said whether what they found on the computer is one of the reasons they arrested Harris.

Father calls in to son's funeral

Though Harris wasn't allowed out of the Cobb County Jail to attend his son's funeral on Saturday in Tuscaloosa, Alabama, 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.

The child's mother had wanted to obtain photos of her son from seized computers for use at the funeral, but Cobb County police turned down her request, said Maddox Kilgore, the attorney for Harris.

Police spokesman Michael Bowman told CNN, "If we have evidence, we will not be releasing that due to chain of custody issues."

Bowman would not confirm what, if any, evidence they had in their possession.

A charity fund at Harris' employer, The Home Depot, will pay for the funeral, company spokeswoman Catherine Woodling told CNN. Harris, who worked as a Web designer, has been placed on unpaid administrative leave, she said.

The funding of the funeral from the Home Depot charity, the Homer Fund, is a "standard approach," she said.

'What have I done?'

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.

"The chain of events that occurred in this case does not point toward simple negligence, and evidence will be presented to support this allegation," said Cobb County Police Chief John House.

A criminal warrant released Wednesday described the events that led to Cooper's death.

A timeline of events

On the day Cooper died, Harris 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.

A wave of sympathy

Each year, dozens of children die from heatstroke in cars, according to KidsandCars.org. More than 40 died last year. The organization says its tally is likely incomplete and much lower than the real toll.

The charging of Harris triggered a wave of sympathy and a vigorous debate over whether the heartbroken father should be punished.

this note: "I think that based on the recent developments this petition is no longer relevant. I still pray that this was truly an accident. If that is the case, the DA now knows that the community does not want Justin prosecuted on murder charges." Two change.org petitions urging authorities to release Harris were started and then shut down this week. One petition posted this note: "I think that based on the recent developments this petition is no longer relevant. I still pray that this was truly an accident. If that is the case, the DA now knows that the community does not want Justin prosecuted on murder charges."

Another, set up at YouCaring.com, has raised more than $22,000 for the Harris family.

"Please don't listen to the media. It just upsets me to watch it," wrote Heather McCullar, who set it up. "Please don't listen to the media. The family will speak when they can."

Contacted by CNN via e-mail, she wrote back, "No one is allowed to comment right now."

'The manner of death is homicide'

As Harris sits in jail, his wife, Leanna, would not discuss the case with the media.

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 Wednesday. Temperatures hit 92 degrees Fahrenheit on the day of his 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.