"There is a lot of speculation and a lot of innuendo," Officer Mike Bowman told PEOPLE on Thursday, referring to reports that the child's father, Justin Ross Harris, did an Internet search for how long it takes for an animal to die in a hot car. "We are not releasing anything of evidentiary value. Our detectives are working tirelessly and with due diligence to make sure this case is not tainted, and that we're able to get an impartial jury."
Harris was charged on June 19 with felony murder and second-degree child cruelty, and Cobb County Police Chief John R. Houser issued a statement Wednesday to give details on the charges.
"The chain of events that occurred in this case does not point toward simple negligence, and evidence will be presented to support this allegation," Houser said. "During the course of their investigation, detectives began to obtain physical evidence and testimonial evidence that led them to believe a more serious crime has been committed."
The statement has caused public support for Harris to wane – a group called Parents Support Parents withdrew an online Change.org petition Thursday that had been signed by 10,000 people requesting charges against Harris be dropped.
Fundraising Drive Still ActiveOrganizers left a message on the site, explaining their reason for dropping the petition: "Hello. I think based on the recent developments this petition is no longer relevant." An online fund-raising drive that had raised more than $22,000 for Harris's defense is still active.
The withdrawal of the petition came the day after an autopsy conducted by the Cobb County Medical Examiner's Office determined that the toddler, Cooper Mills Harris, died of hyperthermia after his father left him in his car seat in a 2011 silver Hyundai Tucson while he worked in the IT department at Home Depot headquarters.
Harris, 33, remains in the Cobb County Jail without bail. His son will be buried Saturday in a private ceremony in Tuscaloosa, Alabama, where Harris attended high school and the University of Alabama. Facebook pictures of the family show a smiling Harris, his wife and baby at an Alabama football game.
The criminal warrant says that Harris and his son left the house around 8:30 a.m. on June 18, after Harris buckled in the toddler into a rear-facing car seat in the backseat of the family's SUV. They then drove away from the rented condo where they lived with his wife and the baby's mother, Leanna Harris.
Resuscitation Efforts UnsuccessfulThe warrant goes on to say Harris drove to a nearby Chick-fil-A, unbuckled and took the baby inside the restaurant. After eating, Harris returned his only child to the car seat and drove just minutes to his office, where he left him strapped in the vehicle while he entered work.
The criminal warrant also stated, "During lunch [Harris] did access the same vehicle through the driver's side door to place an object into the vehicle."
When Harris finished work that day, he drove away, but pulled over at a shopping center, jumped out of the vehicle and yelled for help – bystanders and emergency responders tried to resuscitate the baby but were unsuccessful, according to reports.