BOISE, Idaho (AP) — A federal judge has refused to postpone the execution of an Idaho inmate who is slated to be put to death Friday.

U.S. Magistrate Judge Ronald Bush said in a 43-page ruling Monday that he would not grant a stay of execution to Paul Ezra Rhoades.

Rhoades, who was convicted of killing three people and sentenced to death for two of the murders, is scheduled to die by lethal injection. He is suing the state in federal court, contending that Idaho's execution method can be easily botched and so amounts to cruel and unusual punishment, and he asked Bush to put his execution on hold while the lawsuit works through the courts.

State attorneys countered that Idaho's lethal injection process closely mirrors lethal injection protocol in other states that has already been upheld by the U.S. Supreme Court. The process relies on three drugs administered intravenously: First, an anesthetic meant to make the condemned inmate deeply unconscious, followed by a paralytic that will make the inmate unable to draw breath, and finally a drug that will stop the inmate's heart.

The judge said that he agreed that the execution, if done incorrectly, could leave Rhoades in agony as he dies. But he also said the Idaho Department of Correction has done enough to safeguard against that error.

"The Court agrees with the parties that if Rhoades is not rendered sufficiently unconscious from the first drug used in the three-drug lethal injection protocol, then he will certainly suffer excruciating suffocation and pain from the remaining two drugs. The Court also finds, as agreed by the parties, that if properly anesthetized, there will be no risk of pain for Rhoades."

Bush went on to say that Idaho isn't required to implement a one-drug execution — which essentially overdoses an inmate with an anesthetic — as Rhoades had wanted. The judge said that's because Rhoades didn't make a "more certain showing" that the existing three-drug protocol raises a substantial risk of serious harm.

"The State of Idaho has an interest in seeing that its laws are enforced, and further delay will not meet that interest," Bush wrote.

Rhoades' lawyers said they intend to seek a stay of execution Tuesday from the 9th U.S. Circuit Court of Appeals.

"We remain dedicated to challenging Idaho's lethal injection protocol, as we maintain it could subject Mr. Rhoades to substantial risk of severe pain," said a statement from the federal defender's office. "We will continue to urge Gov. Butch Otter to exercise his executive powers and grant a reprieve until a full hearing can be held before the Parole Commission so that Mr. Rhoades can present a full and accurate picture of his case."

Without such intervention, Bush's ruling appears to clear the way for Rhoades' execution scheduled for Friday at 8 a.m. If the execution happens, it will be Idaho's first in 17 years and the only one in the last half-century to happen without the consent of the condemned inmate.

Rhoades was given two death sentences for the sexual assault and murder of Idaho Falls teacher Susan Michelbacher, 34, whose bullet-ridden body was found in March 1987. He also was given two death sentences for the first-degree murder and kidnapping of Stacy Dawn Baldwin, 21, a Blackfoot convenience store clerk who was shot to death in February 1987.

Rhoades was also sentenced to life in prison without the possibility of parole after pleading guilty to the March 1987 shooting death of Nolan Haddon, 20, a Blackfoot man who worked at an Idaho Falls convenience store.

The state's last execution, in 1994, was of Keith Eugene Wells, who gave up his remaining appeals and asked to be put to death. The prior execution was in 1957.

During a court hearing in Rhoades' case Thursday, Rhoades' attorneys took issue with testimony from a prison official in charge of selecting the execution team members. Bureau of Prisons Chief Deputy Jeff Zmuda said he didn't verify the team members' credentials or training, and said the documents he did review about the team members were destroyed. The judge indicated that he didn't take that contention lightly but carefully weighed the evidence and prior court rulings.

"There is no way to make this judicial proceeding, and the starkness of the decision before the Court, appear as if it is either mundanely routine or somehow freighted with great wisdom because the decision is made by someone who wears a judicial robe," Bush said. "Similarly, the heartwood of logic and adherence to the Rule of Law that the Court seeks to bring to the question cannot hide the ultimate end of a decision adverse to Rhoades."

The message of the Supreme Court in previous rulings is unmistakable, Bush said: Speculation cannot substitute for evidence that some part of the protocol is very likely to cause needless suffering. The evidence that some of the execution team members might have exaggerated his or her credentials is neither sure nor very likely, he said, particularly since they have all taken part in group practices where others would have seen, in action, if the team member was qualified for the job.

Bush also reiterated his belief that Idaho Department of Correction officials have been "playing catch-up" in preparing for the execution. The state could have finalized its execution protocol months or even years ago — instead of weeks — but department officials have since made up for much of the lost time, the judge noted.

Rhoades has an interest in seeing his lawsuit through to its end, Bush said, but the state has an interest in seeing its judgment carried out as well — a process that has taken 24 years so far. The families and communities of the victims in the case also have a compelling interest, he wrote.

"There is much that has been said and written about the uncertainties and expense of death-penalty cases, and the impact that the length of time such cases place upon the families and communities of the victims," Bush wrote. "Continued delay compounds those uncertainties, expenses, and impacts, and therefore is not in the public interest."