A veteran journalist who has witnessed nearly 500 executions says the attempted execution of death row inmate Christa Pike in Tennessee was unlike anything he had seen in decades of covering capital punishment.

Michael Graczyk spent 46 years with a major wire service, covering a wide range of topics but becoming particularly known for his attendance at executions in Texas. Although technically retired, he continues to work freelance covering executions in his home state.

Pike was convicted of the torture and murder of Colleen Slemmer, a 19-year-old originally from Florida. Friends and family described Slemmer as someone who loved to roller skate, smile and help others. She was killed by Pike, then 18, and Pike's then-boyfriend, Tadaryl Shipp, after they met her at a job training camp.

Slemmer's mother, May Martinez, was present in Tennessee for the execution attempt. She told sources afterwards that it "was a mess."

Graczyk has attended executions across Texas, the state that has carried out by far the most executions in the country. According to the Death Penalty Information Center, there have been 1,683 executions in the United States since 1976, when the Supreme Court reinstated the death penalty. Texas alone has carried out 602 of those. In 1982, it became the first state to use lethal injection.

Lethal injection is the most frequently used form of capital punishment in the 27 US states where the death penalty remains legal. The Death Penalty Information Center, a think-tank that does not take a stance on the death penalty, defines a botched execution as one involving "unanticipated problems or delays that caused, at least arguably, unnecessary agony for the prisoner or that reflect gross incompetence of the executioner."

The organisation has compiled a list of 64 botched executions since 1982, 51 of them lethal injections. In at least seven of those cases, executions were halted because an IV line could not be set.

Graczyk said he had never previously witnessed an execution fail after the injection was delivered. "That has never happened here," he said, referring to Texas.

He explained that in Texas, observers are not permitted inside the execution chamber while the IV is being inserted. "So when we get into the chamber, the inmate's already hooked up," he said.

In a standard lethal injection, the IV is typically inserted in the crook of the arm. If that site is not viable, it may be placed in the top of the hand, the leg, the neck or other locations. During successful executions, Graczyk said, inmates become "visibly unconscious after just a few seconds" and are usually pronounced dead 20 to 40 minutes after the fatal dose is administered.

Graczyk views his attendance at executions as a professional duty. "There is no [greater] authority, power, or whatever you want to call it, that state or federal government has over us than the power to take our life," he said.

"I always thought it was important for someone who has no stake in the outcome of a case to be there and to see the law being carried out and to make certain that it is done properly," he said. "That someone is there to see it and tell others: Here's what I saw. Here's what happened."

He also feels a responsibility to keep victims from being forgotten. "I feel bad for the victims in the case," he said. "They are the forgotten folks. They always have been."

Reflecting on the Pike case specifically, he said: "Today, all the emphasis is on the inmate in Tennessee. No tears are being shed, other than the victim's immediate family, for the victim … and I understand that's the business we're in, but it doesn't mean it's right."

Among the executions that have stayed with him most is that of Jonathan Nobles, put to death by lethal injection in Texas in 1998 for the 1986 stabbing murders of two Austin women, Kelley Fraquhar and Mitzi Johnson-Nalley. Nobles sang "Silent Night" as his final words.

"He gets to 'Round yon virgin' and he stops talking," Graczyk said. "That's how long it took for the drug to kick in so he wasn't conscious anymore."

The memory has remained with him for nearly three decades. "To this day, when I'm in church on Christmas, and the choir is singing Silent Night, and all the congregation is joining in Silent Night and they're all, you know, in the spirit of the season and the joy of the season, and I'm thinking of this execution, I'm sure I'm the only one in that congregation that is having that kind of recollection."