A death row inmate in Louisiana scheduled to become the first person in the state to be executed using nitrogen gas has asked for his capital punishment to be carried out using a more humane method.

Louisiana’s oldest death row inmate dies 3 weeks before he was to be state’s first execution in 15 years - “Give me a little time,” Christopher Sepulvado’s ex, who also served time for her son’s murder,

Christopher Sepulvado, 81, died Saturday at the Louisiana State Penitentiary in Angola, Louisiana, "from natural causes as a result of complications arising from his pre-existing medical conditions," according to the Louisiana Department of Public Safety and Corrections.

Christopher Sepulvado, 81, died from "natural causes," the state corrections department said. He was convicted of murder in the 1992 killing of his 6-year-old stepson.

A death row inmate slated to become the first person to be put to death by nitrogen gas in Louisiana is seeking to halt the execution, citing constitutional concerns over the controversial killing method.