Both parents of the two-year-old killed after being left in a hot car in Georgia had researched those types of deaths on the internet.

A search warrant released Sunday said that Leanna Harris researched how hot a car would have to be for an unattended child to die. Her husband, Justin Ross Harris, had previously told police that he researched child heatstroke deaths.

Cooper Harris was 22-months-old when he was left in a car for about seven hours on June 18. The temperature that Atlanta day reached 92 degrees.

Justin, 33, told police that he was supposed to drop his son off at daycare but forgot. He drove to his job at a Home Depot corporate office, and left his SUV in the parking lot with Cooper still strapped into his rear-facing car seat.

Police reported that Justin returned to the car on his lunch break and put something inside. When he got off of work at 4:16 p.m., he drove a few miles before discovering his son. Authorities said he was inconsolable at the scene and screamed "What have I done?"

During interrogation, Justin admitted to police that he had researched how hot it would have to be for a child to die of heatstroke.

"Justin stated that he was fearful that this could happen," a police affidavit read. Leanna also told investigators that she researched hot car deaths because she was afraid it might happen to their son. It is unclear when the parents conducted the searches.

Justin was charged with murder and second-degree child cruelty, and remains in an Atlanta jail without bond.

Cooper was buried Saturday in Tuscaloosa, Alabama. At the funeral, Leanna told mourners that she is standing by her husband.

"Am I angry with Ross? Absolutely not," she said.

"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."