Eugene Gates’ body temperature was as hot as the Texas heat wave, more than 104 degrees Fahrenheit, when he collapsed in a Dallas front yard while delivering mail.

Gates, 66, had carried his iconic U.S. Mail bag through the same wealthy neighborhood for much of his 35-year career, until he died of heat stroke on a stifling day in June. A homeowner who rushed to perform CPR could not revive him.

Gates’ death is part of a storm of allegations that the U.S. Postal Service ignored its own heat safety programs and manipulated official records to hide those actions ahead of an unrelenting summer of extreme heat that killed scores of people across the U.S.

Under its own policy, the agency is required to train letter carriers each spring to recognize the symptoms of heat illness and what to do if they feel sick.

But Gates didn’t receive training, and his managers “falsified” official records before his death to hide it, according to his widow, Carla, and leaders of the National Association of Letter Carriers union who are involved in the grievance. And he’s not the only one.

The mounting accusations by thousands of mail carriers come as the debt-plagued USPS is pushing workers to make faster deliveries amid growing competition and as temperatures catapult to heights never before recorded in human history. Its policies have already drawn scrutiny from some members of Congress for requiring carriers to work during hot periods of the day, raising questions about the Postal Service’s ability to protect its workers from climate change.