Police say the three-year-old girl was not left in the car by a caregiver on Tuesday evening, but didn't provide any further detail about how she got there.
Officers did note that vehicle she was found in was not locked.
"The Edmonton Police Service investigation into this case is now closed," the department said in a short statement issued Thursday afternoon.
"Police will not be able to comment further on the circumstances of the death as it is non-criminal."
Both the Edmonton Journal and CBC have identified the tot as Tsi Tsi Chitekedza.
The local outlets quoted her mother, Grace Vela, as saying she doesn't know how her daughter ended up in the car Tuesday after the family had returned from a splash park.
Vela told CBC she pulled the little girl form the vehicle after finding her seemingly sleeping inside with her thumb in her mouth.
The temperature in Edmonton hit 33 C on Tuesday and humidity levels made it feel more like 43 C.
Paramedics performed CPR and provided hydration before the youngster was taken by ambulance to the Stollery Children's Hospital where she died.
Tsi Tsi is the second child to die in a hot car recently.
In Ontario, a funeral was held earlier this week for a two-year-old boy, who died after being left alone in a sweltering car outside a home in Milton, west of Toronto.
Investigators said Maximus Huyskens died after "being exposed to high-level temperatures for an extended period of time" in a sedan.
They said the child was in the care of his maternal grandmother, while his father was at work and his mother was at an appointment.
No charges have been laid. Police are waiting for the results of toxicology tests.
Another mother in Edmonton is facing charges under provincial child welfare legislation for leaving her three boys in a vehicle with the sunroof open this week.
A passerby saw the boys Tuesday in a vehicle in front of a hardware store and called 911.
The children, between two and six years old, were not hurt.
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