The hour of Thomas Eugene Creech’s death has been set, and it is rapidly approaching.

On Wednesday morning Idaho prison officials will ask the 73-year-old if he would like a mild sedative to help calm him before his execution at the Idaho Maximum Security Institution south of Boise. Then, at 10 a.m. local time, they will bring him into the execution chamber and strap him to a padded medical table.

Defense attorneys and the warden will check for any last-minute court orders that would halt the execution of Creech, who is one of the longest-serving death row inmates in the U.S.

Barring any legal stay, volunteers with medical training will insert a catheter into one of Creech’s veins. He’ll be given a chance to say his last words, and a spiritual advisor may pray with him. Then the state will inject a drug intended to kill the man who has been convicted of five murders in three states and is suspected in several more.

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Creech has been imprisoned since 1974 and was originally sentenced to death for the shooting deaths of John Wayne Bradford and Edward Thomas Arnold. That sentence, however, was changed to life in prison after the state’s sentencing law was found unconstitutional.

Then, in 1983, he was sentenced to death for the murder of David Dale Jensen, who was 22, disabled and serving time for a car theft when Creech beat him to death at the Idaho State Penitentiary on May 13, 1981.

Jensen’s family members described him as a gentle soul who loved hunting and being outdoors during Creech’s clemency hearing last month. Jensen’s daughter was just 4 years old when he died, and she spoke about how painful it was to grow up without a father, piecing together everything she knows about her dad from other people’s descriptions and memories.

In court documents filed late last week, Idaho officials said Creech’s spiritual advisor would be allowed to stand next to Creech with a hand on his shoulder during the execution. The Episcopal bishop will also be able to silently pray over Creech but won’t be allowed to hold his hand or make any noise once the administration of the lethal injection chemical begins, according to the court document. Creech will also be allowed to wear a crucifix, according to the document, and his wife will be seated in the witness area where he can make eye contact with her.

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Creech’s supporters have pushed to have his sentence converted to life without parole, saying he is a deeply changed man who has become a kind and supportive force inside the Idaho Maximum Security Institution cell block where he lives. Several years ago he married the mother of a correctional officer, and former prison staffers said he was known for writing poetry and frequently expressing gratitude for the work done by correctional officers.

During his clemency hearing, Ada County Deputy Prosecuting Attorney Jill Longhorst did not dispute that Creech can be polite and friendly with correctional officers. But she said he is a psychopath — a man who can be charming and likeable but who lacks remorse and empathy for others.

Creech’s attorneys filed a flurry of late appeals hoping to forestall his execution or have his sentence converted to life without release. They included claims that his clemency hearing was unfair, that it was unconstitutional to kill him because he was sentenced by a judge rather than a jury, and that he received ineffective assistance of counsel.

But judges in four courts who reviewed the petitions so far have found no grounds for leniency. Creech's last chance hinges on a petition to the U.S. Supreme Court filed late Monday night, asking that the execution be put on hold so the high court can weigh Creech's claim that prosecutors lied during his clemency hearing, violating his due process rights.

In addition to the Idaho murders, Creech has been convicted of killing both William Joseph Dean in Oregon and Vivian Grant Robinson in California in 1974. He was also charged with killing Sandra Jane Ramsamooj in Oregon that year, but the charge was later dropped in light of his other murder sentences.

In 1973, Creech was tried for the killing of 70-year-old Paul Schrader in Tucson, Arizona, but was acquitted of the crime. Authorities still believe him to be responsible for Schrader’s death, and say that Creech provided information that led them to bodies of two people near Las Vegas and one person near Baggs, Wyoming.

Creech's execution will be the second in the U.S. this year, according to the Death Penalty Information Center. The first was in Alabama last month, when Kenneth Eugene Smith became the first death row inmate to be executed using nitrogen gas. Alabama officials said the method would be humane and predicted death would take place within a few minutes, but Smith seemed to remain conscious for several minutes and appeared to shake and writhe in agony for at least two minutes.

Another execution in Texas is also scheduled for Wednesday — Ivan Cantu was sentenced to die for the fatal shooting of his cousin, James Mosqueda, and his cousin's girlfriend, Amy Kitchen. Cantu has maintained he is innocent.

Idaho’s death penalty was established in 1864, about 26 years before the territory became a state. Since that time, 29 executions have been carried out, according to the Death Penalty Information Center, including the state’s last hanging in 1957.

Executions became rare in the following decades. Though dozens of people have been sentenced to death row since the 1970s, Creech will be only the fourth to be executed by the state since 1957, all of them by lethal injection.

Keith Eugene Wells, 31, was executed in 1994 for the murders of John Justad and Brandi Rains committed in Boise just four years earlier; he had given up his appeals and demanded to be put to death. Paul Ezra Rhoades was executed in 2011 for the 1987 murders of Stacy Dawn Baldwin and Susan Michelbacher in eastern Idaho. Rhoades was also convicted of killing Nolan Haddon that year, and authorities said they suspected him in other deaths as well. Richard Albert Leavitt was executed in 2012 for the 1984 murder of Danette Jean Elg in eastern Idaho.

After Creech's execution, just seven people will remain on Idaho's death row. A handful of those sentenced to death in the state in the past 50 years have died of natural causes, and at least two were exonerated of those crimes. Many others have had their sentences reduced on appeal.

Earlier this year Idaho lawmakers considered adding the death penalty as a possible sentence for people convicted of lewd conduct with a child, but the legislation did not make it through the House of Representatives.