C. North Carolina's Protocol on Execution by Lethal Gas
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Prior to any execution, at least three live tests of the execution chamber are conducted using the chemicals that are used in an actual execution. "Mock" rehearsals are also performed.
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The execution chamber is an airtight compartment. A wooden chair with a high back, arm rests, and foot rests is mounted against the chamber's back wall. A steel door is to the left of the chair (as viewed from the witness chamber), and the control room is to the right. After entering the gas chamber, the condemned offender is placed in the chair, and then restraints are applied to his chest, waist, arms, and ankles. The offender wears a mask during the execution.
The chair is equipped with a metal container beneath the seat. Cyanide pellets are placed in this container. A metal canister is on the floor under the container filled with a sulfuric acid solution. There are three keys in the control room. There are also three executioners, and each executioner turns one key. When the three keys are turned, an electric switch causes the bottom of the cyanide container to open allowing the cyanide to fall into the sulfuric acid solution, producing a lethal gas. Inhalation of this gas is supposed to initially render the offender unconscious.
A heart monitor attached to the offender can be read in the control room by a staff member. After the warden pronounces the offender dead, ammonia is pumped into the execution chamber to neutralize the gas. Exhaust fans then remove the inert fumes from the chamber into two scrubbers that contain water and serve as a neutralizing agent. The neutralizing process takes approximately 30 minutes from the time the offender's death is determined. Litmus paper is used to test the level of lethal gas emissions remaining in the chamber. When the gas is neutralized and the chamber is cleared, staff members wearing disposable protective clothing enter the chamber and remove the offender's body for release to the county medical examiner.
The estimated average length of time that elapses from the time the offender is restrained until death is determined is approximately 38 minutes, though death is estimated to usually occur within 6 to 18 minutes of the lethal gas emissions.
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North Carolina has a written execution protocol which is required by law. A pamphlet summarizing North Carolina's protocol is public information.
http://www.fcc.state.fl.us/fcc/reports/monitor/methmon.html