A convicted Nevada mass murderer is mounting a range of legal challenges to a bid to schedule his execution in early June, including questioning whether the district attorney in Las Vegas really wants the lethal injection carried out at a decommissioned prison in Carson City.

Prosecutor Alexander Chen on Friday said that’s a mistake that will be corrected in court filings next week.

Attorneys for Zane Michael Floyd filed new documents this week asking a state court judge to halt the process at least long enough to determine if the state’s lethal injection procedure would be unconstitutionally cruel and inhumane, and to force prisons officials to show they have the three drugs they would use.

“We would add to that the opportunity to present clemency on behalf of our client,” Floyd’s attorney, Brad Levenson, said in an email. “We are indeed litigating in state and federal court on many serious issues.”

District Attorney Steve Wolfson didn’t immediately respond to messages about documents that Levenson filed Wednesday.

One seeks a stay of execution. The other opposes Wolfson’s request for Clark County District Judge Michael Villani to issue a warrant to set Floyd’s execution date the week beginning June 7.

The prosecutor’s April 15 application for a death warrant specifies that the execution should be “within the limits of the State Prison, located at or near Carson City.”

Villani has scheduled court hearings on May 14. Floyd, 45, was sentenced in 2000 to die for killing four people with a shotgun and badly wounding a fifth in a Las Vegas supermarket in 1999.

He is one of 65 inmates housed on death row at Ely State Prison, a facility 250 miles (402 kilometers) north of Las Vegas and some 260 miles (418 kilometers) east of Carson City where a new lethal injection chamber was built in 2016 at a cost of about $860,000. It has never been used.

Floyd’s attorneys want a judge to force state Department of Corrections officials to say if they’ve changed a procedure posted in July 2018 for a lethal injection that was later called off; to prove they have the drugs they would use; and to demonstrate that witnesses would not be exposed to COVID-19.