McCullough was one of at least five prisoners since mid-June to die of a reported heart attack or cardiac arrest in uncooled prisons where the regions’ outdoor heat indices were above 100 degrees, according to a Texas Tribune analysis of prison death reports and weather data. Another man who died last week in a separate Huntsville prison was only 34.

At least four other prisoners died in hot prisons this month with undetermined causes of death.....

More than two-thirds of Texas’ 100 prisons don’t have air conditioning in most living areas. Every summer, as temperatures routinely soar well into triple digits, thousands of officers and tens of thousands of prisoners are cramped inside concrete and steel buildings without ventilation, save windows broken out of desperation and fans that blow hot air. The heat has killed prisoners, likely contributed to severe staff shortages, and cost taxpayers millions of dollars in wrongful death and civil rights lawsuits over the last decade.

This year, state lawmakers chose again not to put any money directly toward installing air conditioning in the dangerously hot prisons, despite a $32.7 billion budget surplus.