But during an hour-long emergency hearing earlier in the day, members of the court asked lawyers for the attorney general's office and the Department of Corrections what harm would be caused by a delay while questions about the use of lethal injection were more thoroughly reviewed.

"What's the hurry," asked Justice Michael Cherry, during the hearing. "Where's the fire?"

Howard Skolnik, director of the Department of Corrections, said Castillo, 34, had been moved to what is called the "last night" cell across from the execution chamber at about 4 p.m. He had unlimited phone privileges and spent most of his time talking to family members.

Castillo ate what was to have been his last meal of a double cheeseburger and three root beers, and consumed most of a half gallon of pralines and almonds ice cream, which had been purchased outside of the Nevada State Prison because it was not available at the institution.

Skolnik said Castillo had taken a Valium provided by the prison to help him relax before the final parts of the process began, and asked for another after learning that he would not be able to go through with his execution.

"He claimed that he was OK, he seemed OK. He said he was very disappointed," Skolnik said.

Skolnik said two relatives of Castillo's victim did travel from out of state to be in the capital to witness the execution.

The daughter and grandson of Castillo's victim, 86-year-old Isabelle Berndt, were contacted and told of the stay before they arrived at the prison, he said.

"Obviously they were hoping for some kind of closure today which they did not get," Skolnik said. "And the inmate himself had really prepared himself for this execution. He is now faced with a minimum of 60 days of waiting to find out what will happen to him."

Skolnik did not speak personally with Berndt's daughter and grandson. But another corrections official who did speak with them said they plan to write letters to both the Supreme Court and the ACLU and enclose their travel expenses to Carson City for reimbursement, he said.

There was no immediate reaction directly from Berndt's family members.

Castillo's attorney, Assistant Federal Public Defender Gary Taylor, said that when he talked with Castillo earlier in the day, Castillo had not changed his mind about going forward with the execution.

Taylor, honoring Castillo's wishes to have his sentence carried out, was not a party to the ACLU in its challenge of the lethal injection execution method used by Nevada and many other states.

Gary Peck, executive director of the ACLU of Nevada, praised the court's order.

"This is good news for the Constitution and the Bill of Rights," he said. "The Nevada Supreme Court in its infinite wisdom saw fit to take the time to carefully consider a profoundly important issue regarding fundamental rights."

ACLU attorney Lee Rowland, who argued much of the case before the Supreme Court, said the delay to more fully consider the issues was the right decision. "I really do think Justice Cherry hit the nail on the head when he asked where's the fire," she said.

Rowland expressed sympathy to the victim's family who made the trip to the capital.

"But this wasn't about what happens to Mr. Castillo," she said. "This is about limitations on the power of the state."

Rowland said the court in deciding to issue the stay may also have considered whether Nevada wanted to have the dubious distinction of being the last state to use lethal injection ahead of a U.S. Supreme Court ruling that could find it a cruel and unusual punishment.

The U.S. Supreme Court agreed Sept. 25 to take a hard look at the method of lethal injection most states use. The high court will hear a challenge early next year from two inmates in Kentucky who claim that lethal injection as practiced by that state amounts to cruel and unusual punishment, in violation of the Eighth Amendment.

One of the issues raised by the ACLU in the emergency hearing before the Supreme Court is whether one of the three drugs used in the execution served only to mask the reaction of the condemned inmate to the final drug that induces death, thus violating the First Amendment by not allowing the public and media representatives to see the full effect of the process.

The argument is that the second drug, pancuronium bromide, a paralytic drug, is used only to veil the reaction of the inmate to his death.

"This component of the protocol creates a chemical curtain, blocking any observers' view of the true nature of the execution," the ACLU said in its emergency petition.

Daniel Wong, chief solicitor general representing the Department of Corrections, said media representatives are able to view the entire execution process. The second drug is used in the process to stop the inmate's breathing, he said.

The third drug, potassium chloride, stops the heart. The first drug, sodium thiopental, is intended to render the inmate unconscious.

Rowland said sometimes an inmate can struggle back into consciousness after the first drug, then feel the pain of death without being able to react because of the paralysis from the pancuronium bromide.

The issue will now be presented to the court in more detailed briefings over the next two months.

Castillo admitted he killed Berndt, but he never said why.

At trial, prosecutors said Castillo attacked Berndt with a tire iron as she slept in her bed in her home near Decatur Boulevard and U.S. Highway 95 during the early-morning hours of Dec. 17, 1995. Castillo and an accomplice had been burglarizing her home at the time.

Castillo returned a short time after the killing and set the house on fire.

Evidence at trial showed Castillo had worked on Berndt's roof over the Thanksgiving weekend in 1995 and found a hidden house key, which he used to enter her home on the morning of the slaying.

His accomplice, Michelle Platou, pleaded guilty to murder and other charges and was sentenced to life in prison with a chance for parole after 20 years. She is serving her sentence at the Southern Nevada Women's Correctional Center.

Castillo would have been the 12th man to die in Nevada by lethal injection. Nevada has used lethal injection to execute death row inmates since it was adopted by the Legislature in 1983. It was first used in 1985 and was last used to execute Daryl Mack in April 2006.