COLUMBIA, S.C. – A South Carolina man who is scheduled to die next week by firing squad is again asking that his execution be postponed and prison officials release more information about the state’s lethal injection drug and procedures.

Lawyers for Brad Sigmon said he is being forced to choose a violent death by firing squad because without more information he thinks he could die a tortuous death if he picked lethal injection.

Sigmon’s attorney said autopsy results from Marion Bowman’s Jan. 31 execution released earlier this week showed he needed twice the dose of the lethal injection drug typically used in other states and by the federal government, according to court papers filed Wednesday with the state Supreme Court.

An autopsy for Richard Moore, who was executed on Nov. 1, found the same amount of pentobarbital was used to kill him over two doses given 11 minutes apart, according to his autopsy.

South Carolina’s execution law requires officials to keep secret the doses of drugs used, how they are administered, who provides the pentobarbital and the names of members of the execution staff. Because of the secrecy, it’s not known if the new procedures put in place last year require two doses of pentobarbital.

South Carolina has said its methods are similar to other states that use one dose of pentobarbital. In Georgia and Tennessee, only one 5 gram dose of the drug is scheduled for the start of the execution. The autopsy findings for Bowman and Moore showed they had 10 grams of the lethal injection drug in their systems.

Sigmon, 67, is scheduled to be put to death on March 7. He was convicted in the 2001 baseball bat killings of his ex-girlfriend’s parents at their home in Greenville County. Sigmon was trying to kidnap his ex-girlfriend and confessed that he was likely going to kill her and then himself. He forced her into his car when she arrived at her parents’ home, but she jumped out of it as Sigmon drove and escaped.

Sigmon’s lawyers also said they want the state to release more information about the lethal injection drugs including how the drug is stored, its expiration date and details about how officials test it to make sure of its potency and purity.

They said Sigmon was forced into choosing a brutal death in what would be the first firing squad execution in the U.S. since 2010 because he feared the state’s lethal injection procedure — if carried out improperly — would leave him to drown from an accumulation of fluid in his lungs.

“Mr. Sigmon will be executed in nine days by a method that he chose out of necessity, fear of a torturous death, and without the information needed to assess his alternatives,” Sigmon’s lawyers wrote.

Previous arguments that the state didn’t release enough information about the lethal injection drugs have been rejected by the South Carolina Supreme Court after state officials said fluid is often found in the lungs of prisoners killed by lethal injection.

The state also cited accounts by witnesses and other evidence that the three inmates executed in the past six months by lethal injection showed no signs of consciousness or breathing after about a minute — even if they weren’t declared dead for over 20 minutes after the execution started.

Freddie Owens, the first inmate killed with the new protocols, refused an autopsy for religious reasons.

If the execution is carried out as planned, Sigmon is to be strapped to a chair in the death chamber and have a hood placed over his head and a target placed over his heart. Three volunteers, all with live ammunition, would then fire at him through a small opening about 15 feet (4.6 meters) away.

State law allows inmates to die by firing squad, lethal injection or the electric chair. Sigmon’s lawyers said he also didn’t choose the chair because he said he didn’t want to be cooked alive.

“Brad Sigmon has repeatedly asked for the basic facts needed to determine if South Carolina’s drugs are expired, diluted, or spoiled. He has thus far been denied. He chose the firing squad because he was unwilling to risk the prolonged, torturous death that he fears his friends endured. Mr. Bowman’s autopsy confirms that those fears were justified,” lawyer Gerald “Bo” King wrote in a statement Wednesday.