BATON ROUGE — Louisiana laid out details Thursday on how its prison system plans to kill an inmate later this month, describing a series of practice runs the execution team at Angola will make and the steps it will take to ensure that the condemned prisoner is the only person killed.

Jessie Hoffman is scheduled to die March 18 by nitrogen hypoxia for the 1996 rape and murder of Mary "Missy" Elliot, a 28-year-old advertising account executive from New Orleans. Her body was found in a secluded area near the Pearl River in St. Tammany Parish.

Under the protocol adopted last month, an unnamed executioner will administer nitrogen to Hoffman via a tightly fitted mask, replacing the oxygen in his body. An expert for the state says Hoffman should be unconscious within seconds, but the nitrogen will flow for at least 15 minutes or for 5 minutes after a heart monitor shows no electrical activity.

Describing "general safety requirements" to be used around the nitrogen, the state says wall-mounted "oxygen-deficient atmosphere" monitors will be placed in three rooms — the execution chamber, an "oxygen and inert gas" room and the witness area. Each would sound an alarm if the air is not at least 19.5 percent oxygen; and eight portable oxygen monitors will be distributed to those in the execution chamber and inert gas room.

The state and Hoffman's lawyers released a redacted version of the protocol Thursday. U.S. District Judge Shelly Dick had given them until Thursday morning to agree on what material should be disclosed. Hoffman is challenging Louisiana's death penalty procedures and a court hearing is set for Friday morning.

The protocol from the Department of Public Safety and Corrections is similar to those found in many other states and drills into some fine detail, including what Hoffman will wear and how execution personnel will check to ensure Hoffman is dead. A funeral home director will prepare a death certificate and the body will be handled in a manner worked out with the inmate.

Members of the execution team are granted anonymity, except the warden of the State Penitentiary at Angola, and a variety of state laws prohibit their being disciplined by state licensing boards for their participation —  for example, doctors take oaths to preserve life but are allowed to take part in executions under the protocol. 

The policy also lets prison employees who don't want to take part an execution a right to opt out without reprisal.

The policy also lays out the method for an execution by lethal injection, though the drugs used for them are unavailable. Pharmaceutical companies have told states that if they use their products to kill inmates they risk losing access to medicines used to treat non-condemned inmates.

Alabama is the only state to have used nitrogen hypoxia to kill inmates. It has executed four under its current protocol.