The order will come: "Ready, aim..."
The 49-year-old convicted killer will be executed by a team of five anonymous marksmen firing with a matched set of .30-caliber rifles. He is to be the third person executed by firing squad in Utah - or anywhere else in the U.S. - since the death penalty was reinstated in 1976.
Utah was a long holdout in keeping the method, which it has used in 40 of its 49 executions in the last 160 years. Utah lawmakers made lethal injection the default method of execution in 2004, but inmates condemned before then can still choose the firing squad.
That's what Gardner did in April, politely telling a judge, "I would like the firing squad, please." Neither he nor his attorneys have said why.
Critics decry the firing squad as a barbaric method that should have been relegated to the dustbin of the frontier era.
"The firing squad is archaic, it's violent, and it simply expands on the violence that we already experience from guns as a society," Bishop John C. Wester, of the Roman Catholic Diocese of Salt Lake City, said during an April protest. The diocese is part of a new coalition pushing for alternatives to capital punishment in Utah.
Even some death-penalty supporters would prefer not to see the method used. State Rep. Sheryl Allen, a Republican from Bountiful who pushed for the switch to lethal injection, said she's not happy to see the reprise of the firing squad because it shifts attention away from the victim to the convicted killer.
Gardner is to be executed June 18, shortly after midnight. He was convicted of capital murder 25 years ago for the 1985 fatal courthouse shooting of attorney Michael Burdell during a botched escape attempt.
Allen said legislators allowed previously convicted inmates to keep the firing-squad option out of fear that changing the execution method would create a new avenue of appeal.
Utah's switch to lethal injection was largely driven by an aversion to the negative worldwide publicity it received each time a firing squad was used, including the case of Gary Gilmore. The convicted killer famously proclaimed "Let's do it" before his 1977 execution by a firing squad. Gilmore's story inspired author Norman Mailer's Pulitzer Prize-winning novel, "The Executioner's Song."
Utah last used the firing squad in 1996 to execute John Albert Taylor, who was convicted of the 1989 rape and strangulation of an 11-year-old girl. It is the only state that allows execution by firing squad, though Oklahoma law calls for that method if both lethal injection and electrocution are deemed unconstitutional.
Officials with the Utah Department of Corrections declined to be interviewed by The Associated Press about the details of Gardner's execution, citing security concerns.
In its planning, the department will likely rely heavily on a manual for conducting executions - by firing squad and lethal injection - written in 1986 by Gary DeLand, who ran Utah's corrections agency in 1985-92 and was later tapped to rebuild Iraq's prison system.
DeLand planned three executions for the state of Utah, including one for Gardner in the 1990s that was delayed by a court order two days before the scheduled date.
Based on DeLand's own description of the planning, written accounts of past executions and the recollections of former department employees, at some point in the 24 hours before the execution, Gardner will be moved from his 6-by-12-foot, maximum-security cell to a deathwatch cell where he can be more closely monitored by guards.
After Gardner is allowed the customary last meal and visitors, prison guards will strip search him and give him a dark-colored prison jumpsuit to wear to the 20-by-24-foot execution chamber.
Inside, Gardner will be strapped into a winged, black metal chair with a mesh seat that was built for Taylor's execution. A metal tray beneath the chair is designed to collect any blood that runs from the executed prisoner's body.
For Taylor's execution, sandbags were stacked behind the chair to catch any stray bullets.
Aside from staff, as many as 25 individuals may witness the execution from three observation rooms that surround the execution chamber, according to the department memo. The witnesses include relatives of the victims, representatives for the state, news media and individuals selected by Gardner.
Once the witnesses are in place, the prison warden will open the curtains on the observation room windows. Gardner will be asked for any last words.
Then, after a final check for a stay with the Utah attorney general's office, comes the order to the executioners, who fire from a distance of about 25 feet.
The gunmen stand behind a wall cut with a gunport, their rifles bench-rested to assure accuracy, DeLand said.
The guns are handed out randomly to the officers. One will be loaded with a blank, so no one will know who fired the fatal shot. By law, the identities of those selected for the firing squad remain secret.
A state judge signed the warrant ordering Gardner's execution on April 23. That launched a flurry of legal filings by attorneys aimed at getting Gardner's death sentence reduced to life in prison without the possibility of parole.
So far those attempts have been unsuccessful, although the Utah Supreme Court is scheduled to hear an appeal on Wednesday and the state parole board is to begin a two-day commutation hearing Thursday.
Gardner and his attorneys can continue to try and stop the execution up until midnight on June 17, Assistant Utah Attorney General Tom Brunker said.
No matter what happens in Gardner's case, America's last execution by firing squad could be years off. At least three of the other nine men on Utah's death row have said they want to die that way, too.