HOUSTON (AP) — The Texas prison system's 100 units have been placed on a statewide lockdown due to a series of drug-related inmate homicides, officials announced on Wednesday.

But the lockdown is worrying advocates for inmates who say the order could endanger the lives of many prisoners during an unrelenting summer heat wave. During the lockdown, inmates will be confined to their cells, many located in prisons with no air conditioning. Much of Texas was expected to again be under heat advisories this week.

"It's going to make the heat situation worse. This is not the time to do a lockdown. In the summer months, it's not the time," said Amite Dominick, the founder and president of Texas Prisons Community Advocates, a group that supports inmates and their families.

Advocates and others have been highly critical of the lack of air conditioning in the nation's largest prison system. They alleged temperatures that often go past 120 degrees Fahrenheit (48.9 degrees Celsius) inside Texas prisons in the summer have been responsible for hundreds of inmate deaths in recent years. Only about 30% of Texas' 100 prison units are fully air-conditioned, with the rest having partial or no air conditioning. Texas has about 128,000 inmates.

However, the Texas Department of Criminal Justice, or TDCJ, says there have been no heat-related deaths in the state's prisons since 2012.

TDCJ said the lockdown was in response to "a rise in dangerous contraband and drug-related inmate homicides" due in part to an increase over the last five years of illegal drugs coming into state prisons.

The agency said there have been 16 inmate-on-inmate murders this year, with most believed to be connected to illegal drugs. In 2021, there were nine such murders while in 2022 there were seven.

"A lockdown is a necessary response to confront the root causes of this crisis, enhance security measures, and ensure the well-being of all individuals within our agency," TDCJ Executive Director Bryan Collier said in a statement. "We are committed to finding the narcotics, but also working with the Office of Inspector General and outside law enforcements to dismantle the networks that are trafficking drugs into our systems."

While Texas prison units go into lockdown at least twice a year at different times, a systemwide lockdown is rare, TDCJ spokeswoman Amanda Hernandez said in an email.

During the lockdown, prison officials will be taking action to combat the smuggling of illegal drugs, including intensified searches of inmates, staff and others entering facilities, increased drug testing and the creation of a tip line.

TDCJ said it's moving forward with its digital mail rollout, which will scan and convert all inmate mail into digital form that can be viewed on tablets. The change was done because of a significant increase in drug smuggling through letters soaked in methamphetamines or other illegal substances, officials said.

Officials suspect that a combination of smuggling by inmates, prison guards and through the mail is responsible for the majority of drugs coming into units, Hernandez said.

Heat protocols will still be followed during the lockdown, Hernandez said. These include giving inmates access to ice water, cold showers and areas with air conditioning.

But Dominick said inmates and families her organization has worked with have told her such heat protocols are not being followed by TDCJ.

Gregory Goodnight, an inmate at the Estelle Unit in Huntsville, told The Associated Press in a July 18 letter that the conditions he and other inmates have faced because of the heat were "cruel, potentially deadly and illegal." Goodnight said his unit, which houses inmates with medical conditions, has no air conditioning in its cells or hallways, there's insufficient air circulation and many days inmates don't get a shower.

Visits to inmates by their families and others have been canceled during the lockdown.

"If we're talking about people abusing drugs, one of the things that will inoculate or help a person to not be caught up in that addiction is family support. And so, they're cutting off the main means of family support" by canceling visitations, Dominick said.

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