LAS VEGAS — A Nevada inmate slated to die by a three-drug lethal injection combination never before used in the U.S. has said repeatedly he wants his sentence carried out and he doesn’t care if it’s painful.

But a last-minute lawsuit filed by a drug company that doesn’t want its product used in “botched” executions could derail Scott Raymond Dozier’s scheduled Wednesday execution.

New Jersey-based Alvogen filed documents Tuesday in state court in Las Vegas declaring that Nevada prison officials illegally obtained the sedative midazolam, and demanding it be returned and not used as the first of three drugs in Dozier’s execution.

“Midazolam is not approved for use in such an application,” the document said, adding uses of midazolam in other states “have been extremely controversial and have led to widespread concern that prisoners have been exposed to cruel and unusual treatment.”

It was not immediately clear if the filing would stop the execution scheduled at Ely State Prison, 250 miles north of Las Vegas. Clark County District Court spokeswoman Mary Ann Price said the company would also need to file with Judge Elizabeth Gonzalez a request for a court order to halt the proceeding.

Midazolam was substituted in May for expired prison stocks of diazepam, a similar sedative commonly known as Valium.

Drug company Alvogen said it didn’t want one of its products, Midazolam, used in a three-drug lethal injection combination scheduled for an execution Wednesday.

Dozier, a twice-convicted killer who attempted suicide in the past, has said he prefers death to a life in prison.

“I’ve been very clear about my desire to be executed … even if suffering is inevitable,” he said in a handwritten note to a judge who postponed his execution in November over concerns the untried drug regimen could leave him suffocating, conscious and unable to move.

Dozier repeated his desire to die during recent interviews with the Reno Gazette Journal and Las Vegas Review-Journal.

“Life in prison isn’t a life,” the 47-year-old inmate told the Review-Journal.

Dozier, the son of a federal water engineer, grew up in Boulder City, Nevada, and attended high school in Phoenix. He is an honorably discharged Army veteran; a divorced father who became an emergency medical technician during his then-wife’s high-risk pregnancy; a pastels painter; a landscaper; and a methamphetamine user, maker and dealer.

He was close to his grandfather, who killed himself when Dozier was 5. He told a clinical psychologist who testified at his trial that he was sexually abused by a teenage male neighbor from ages 5 to 7.

The psychologist diagnosed Dozier with anti-social personality disorder with narcissistic traits.

There’s a limit to how much artwork and exercise a person can do in prison, Dozier said in court hearings and letters to Clark County District Court Judge Jennifer Togliatti, the Las Vegas judge who postponed his execution.

Togliatti presided over the 2007 trial in Nevada in which a jury decided Dozier should die for murder convictions in Arizona and Nevada in separate slayings of drug-trade associates, according to court records.

In 2005, Dozier was sentenced to 22 years in prison for the shooting and mauling of 26-year-old Jasen Greene, whose body was found in 2002 in a shallow grave outside Phoenix. A witness there testified that Dozier used a sledgehammer to break Greene’s limbs so the corpse would fit in a plastic tote that Dozier used to transport methamphetamine, equipment and chemicals.

Dozier was sentenced to die for robbing, killing and dismembering 22-year-old Jeremiah Miller at a Las Vegas motel in 2002. Dozier also used names including Chad Wyatt.

Miller had come to Nevada from Phoenix to buy ingredients to make meth. His decapitated torso was found in a suitcase in an apartment building trash bin, also missing lower legs and hands. He was identified by tattoos on the shoulders. His head was never found.

Family members of Dozier’s victims are not expected at his execution, Nevada prisons spokeswoman Brooke Santina said. Several Dozier family members are expected to attend.

Dozier suspended any appeals of his conviction and sentence, which would make him one of about 10 percent of the 1,477 inmates who gave up appeals and were executed nationwide since 1977, according to the Death Penalty Information Center in Washington, D.C. Critics say he is seeking state-assisted suicide.

Dozier has not responded to messages through his lawyers to speak with The Associated Press.

He did, however, let federal public defenders review and challenge the execution protocol drawn up last year by state medical and prison officials. They argued the untried three-drug combination would be less humane than putting down a pet.

Togliatti invited state Supreme Court review, saying she expected the Nevada execution to be closely watched by officials in states that have struggled in recent years to identify and obtain drugs from pharmaceutical companies that don’t want their products used for the death penalty.

Pfizer protested last year, but Nevada refused its demand to return the diazepam and fentanyl it manufactured.

The state high court in May decided on procedural grounds that the execution could go forward, but did not review the three-drug protocol that death penalty experts have characterized as experimental and risky.

“Because Nevada is using a combination of drugs that no one has used before, there is a lot about its protocol that we don’t know anything about,” said Robert Dunham, death penalty center executive director.

The midazolam is expected to render Dozier unconscious before he is injected with the powerful synthetic opioid fentanyl, which has been blamed for overdoses nationwide but has not been used in an execution. That will be followed by the muscle paralyzing drug cisatracurium.

Midazolam has been used with inconsistent results in states including Alabama, Arkansas, Arizona, Florida and Ohio. Dunham noted the 2014 executions of Dennis McGuire in Ohio and Joseph Rudolph Wood III in Arizona left both inmates gasping and snorting before they died.

Nevada’s last execution occurred in 2006, when Daryl Linnie Mack asked to be put to death for his conviction in a 1988 rape and murder in Reno.