BATON ROUGE — Lawyers for an inmate scheduled for die by nitrogen hypoxia next month said Wednesday they had filed a federal lawsuit hoping to stop the execution, noting that Louisiana doesn't even allow veterinarians to euthanize dogs and cats by gassing them.

The lawyers are also seeking a court order to stop Jessie Hoffman's execution, which is set for March 18. Hoffman was convicted of kidnapping a New Orleans advertising executive and taking her to St. Tammany Parish, where she was raped and shot dead in a wildlife area near the Pearl River. Mary "Molly" Elliot was 28.

Gov. Jeff Landry this month announced Louisiana could restart executions this year after developing procedures for killing inmates with nitrogen. He put out a brief statement outlining the protocol but the protocol itself remained under wraps. 

Hoffman's lawyers say they were denied access to the protocol due to the "erroneous and irrelevant contention" that the means of conducting executions in Louisiana are not subject to the state's open records law.

Alabama previously adopted nitrogen hypoxia as a means of execution. In cases there, inmates are fitted with a mask and administered nitrogen, which replaces oxygen in the inmate's body.

Associated Press writer Kim Chandler wrote last February that when Alabama conducted its first execution using nitrogen, the inmate convulsed for several minutes and that the procedure lasted 22 minutes. According to the lawsuit, "each of the four times it has been used it has resulted in an excruciating, prolonged death that was horrifying for both the person being executed and those who bore witness."

Hoffman's lawyers also say that Louisiana bars using gas to euthanize dogs and cats because of the distress asphyxia causes them. The prohibition has been in place since 2013.

The lawyers also say that, as a Buddhist, Hoffman practices meditative breathing and that administering nitrogen to him will prevent him from practicing his faith as he is killed. Hoffman's lawyers said also that the inmate has asked Landry for clemency.

The state had scheduled Christopher Sepulvado to die March 17, but the 81-year-old died in prison last weekend. He had been convicted of killing his stepson three days after marrying the boy's mother.

A separate lawsuit challenging the state's execution protocol was halted this week by the 5th U.S. Circuit Court of Appeals. That lawsuit is based on a previous challenge to Louisiana law.