Last week, Democrats including San Antonio-Austin Congressman Greg Casar called on lawmakers to open an investigation into prison conditions in Texas.

At least 41 people have died in the Lone Star State’s unairconditioned prisons due to heat-related or unknown conditions this summer, according to the Texas Tribune.

Even so, it’s hard to firmly establish how many have succumbed to heat-related illness, according to observers. That’s because TDCJ’s official stance is that no inmates have died of heat exhaustion since 2012 — the same year the agency began to be bombarded with wrongful death lawsuits from inmates’ families, the Tribune reports.