An autopsy report revealed the cause of death for the three family members whose bodies were found decomposing in a Brownsville apartment in May.

All three individuals had a medical history that was complicated by "environmental heat exposure," according to Cameron County Justice of the Peace for Precinct 2 Linda Salazar.

RELATED STORY: Three decomposed bodies found in Brownsville apartment, investigation underway

The air conditioner in their apartment was reportedly not working, and the heat index in the days leading up to the discovery of the bodies was in the triple digits, accoridng to the autopsy report.

The victims, identified as 60-year-old Maria E. Singh, 82-year-old Joaquin Galvan and 78-year-old Maria T. Galvan, were found dead in a "high state of decomposition" at the Conquistador Apartments, located at the 300 block of Billy Mitchell Boulevard, on May 8.

Police were conducting a welfare concern when they discovered the bodies. 

Singh was the caretaker for siblings Joaquin and Maria.

RELATED STORY: Bodies found in Brownsville apartment identified as members of the same family

The report said Singh had a history of diabetes, Joaquin had a history of diabetes, hypertension and hyperlipidemia with chronic kidney disease and peripheral quadriplegia, and Maria had a history of diabetes, hypertension, and hypothyroidism with congestive heart failure.

The report said there were multiple floor fans in operation inside the apartment and the AC was not working. The temperature inside the apartment was 88 degrees, compared to the outside temperature, which was at 85 degrees.

"Over the preceding three days, the temperatures ranged from 90 to 94 degrees Fahrenheit... heat index range 102 to 108.6 degrees Fahrenheit," the report stated.