Arizona Testing Gas Chambers For Capital Punishment Using Zyklon B, Documents Show


Jack Dunhill


Jack Dunhill

Social Media Coordinator and Staff Writer

Jack is a Social Media Coordinator and Staff Writer for IFLScience, with a degree in Medical Genetics specializing in Immunology.

Social Media Coordinator and Staff Writer

zyklon b

Empty Zyklon B containers discovered in Auschwitz. Image Credit: Stanislav Samoylik /

Since the death penalty was introduced to the US in 1608, various methods have evolved in an attempt to enact the sentence in the most "humane" way possible. Hanging, firing squads, and the electric chair all made appearances throughout history, but lethal injection quickly became the only remaining method in most states with capital punishment.  

However, as pharmaceutical companies became reluctant to sell lethal doses of drugs for the death penalty and anesthetic supply dwindled, some states have turned to more classical forms of punishment. On May 14 this year, governors in South Carolina turned to any means necessary to carry out the deadly blow, signing a bill that enabled prosecutors to use firing squads and electrocution to kill the perpetrators where the lethal injection is not possible. 


One state, though, is taking a different approach. 

According to public documents obtained by an investigation by The Guardian, the state of Arizona may be preparing to bring back hydrogen cyanide within gas chambers as a form of capital punishment. Hydrogen cyanide, sold by the brand name Zyklon B, was used extensively by the Nazi party during the Holocaust and was utilized in gas chambers as lethal punishment during the 1900s, but has not been used by Arizona state since 1999.  

Despite its’ lack of use, the new documents show a $2,000 payment by the Arizona department of corrections to purchase ingredients to make cyanide gas, as well as efforts to refurbish their old gas chambers at ASPC-Florence. During August, a number of tests were conducted to assess their operability, and it is thought the state may begin to reintroduce the method if tests are successful. As the Guardian points out, the tests conducted to ensure the chamber was airtight included some pretty primitive methods, such as holding a candle to possible leaking areas to see if the flame flickered. 

The documents state that the gas chamber operates by combining potassium cyanide and sulfuric acid, creating hydrogen cyanide that is then contained within the chamber. It is by no means a peaceful way to die, with the last case of gas chamber execution in Arizona taking 18 minutes for Walter LaGrand to die. 


The revelation comes after attitudes have shifted away from lethal injection, which caused an outcry in 2014 when inmate Joseph Wood suffered an agonizing death at the hands of executioners. After using a new cocktail of lethal drugs, Wood required 15 times the recommended amount before succumbing to the injection, and the whole ordeal lasted almost 2 hours. Since then, Arizona has looked for alternative methods, but refuses to stray away from capital punishment. 

There are currently 115 inmates on Death Row in Arizona, awaiting their sentence. Drug shortages have resulted in a backlog of executions, which the state is eager to restart. There has been no official statement on the potential use of gas chambers yet, so it is unknown whether the testing was hypothetical, or whether the state intends to go forward with the plan.



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  • hydrogen cyanide,

  • death penalty,

  • Arizona,

  • capital punishment,

  • zyklon b,

  • gas chambers