Sandra Yi, a reporter with KSLTV in Utah, said Gardner fidgeted even after the barrage of gunfire.
"When he was shot, some of us weren't sure if he had passed away because we could see movement," she said. "He had his fist clenched and we could see his elbow move up and down."
Sheryl Worsley, a reporter with KSL News Radio in Utah, described the moments after the execution as disturbing.
"He moved a little bit and, to some degree, that bothers me," she said. "To some degree that mirrors the last few weeks of his life because he was fighting to stay alive the last few weeks and that seemed to continue on."
Prison officials said Gardner spent his final hours sleeping, reading the spy thriller "Divine Justice," and watching the "Lord of the Rings" film trilogy. He also met with his attorneys and a Mormon bishop. He appeared relaxed. He had fasted after eating his last requested meal -- steak, lobster tail, apple pie, vanilla ice cream and 7-Up -- two days earlier.
"He was at peace," his attorney, Tyler Ayres, told The Salt Lake Tribune. "He even laughed a few times ... and that helped put me at ease."
Outside the prison, members of his family -- some wearing T-shirts displaying his prisoner number, 14873 -- gathered to pay their respects. They were joined by dozens of death penalty protesters. Around the time of the execution, family members cranked up a car stereo playing Lynyrd Skynyrd's "Free Bird."
"He didn't want nobody to see him get shot," said Gardner's brother, Randy Gardner. "I would have liked to be there for him. I love him to death. He's my little brother."
To the end, Gardner's attorneys argued the jury that sentenced him to death in 1985 heard no mitigating evidence that might have spared him with a life sentence. They described him as a disturbed man whose life was marked by early drug addiction, physical and sexual abuse and possible brain damage.
"I had a very explosive temper," Gardner admitted in court.
After a reprieve was denied by Gov. Gary Herbert late Thursday, Gardner became the third person to die before a firing squad in Utah or anywhere else in the nation since the death penalty was reinstated in 1976.
It had been 14 years since rifles last were fired in a state execution.
"Upon careful review, there is nothing in the materials provided this morning that has not already been considered and decided by the Board of Pardons and Parole or numerous courts," Herbert said in a statement.
Utah is the last state that still conducts executions by firing squad.
The simple mechanics of an old-fashioned execution by firing squad are cold blooded, efficient and have just a hint of consideration for the person living his last moments.
Gardner's final procession toward this moment began earlier this week. He was moved at 9 p.m. Wednesday from his 6-by-12-foot cell on death row to a death watch cell near the execution chamber. Prison guards monitored him round-the-clock.
Execution by firing squads date back as far as firearms themselves, but they are rare in the United States. Utah has used firing squads in 41 of its 50 executions in the last 160 years.