Authorities were called to a home on the 1200 block of Schuylkill Avenue back on May 28 for reports of a 6-year-old girl in cardiac arrest.
At the scene, police say the girl was placed in an ambulance, but it appeared she had been dead for a period of time.
An investigation revealed that the victim had been in the care of her grandmother Jazmine Rodriguez, her grandfather Manuel Rodriguez Sr., and her uncle Manuel Rodriguez Jr.
Officials say the results of the victim's autopsy were released earlier this week. Her cause of death has been ruled as a homicide.
According to the medical examiner, the child died due to dehydration and prolonged exposure to the heat due to child neglect.
Authorities say the girl had been left in a soiled diaper for several days before her death, leading to severe rashes.
They also found that the lack of air circulation and the temperature of the room where the girl was sleeping may have hit 100 degrees with 90% humidity.
The medical examiner stated that the girl's death was consistent with her having been locked in a room for more than three days.
On Monday, Jazmine and Manuel Rodriguez Sr. were taken into custody.
Authorities say Manuel Rodriguez Jr. is still at large.
Anyone with information on this incident is asked to contact Reading police.