Writing for the Arkansas Times and Guardian, Rosenberg has described in detail his experience watching the execution of Marcel Williams who was condemned to death row over the 1994 rape and murder of 22-year-old Stacy Errickson.
After being led to the viewing window of the Cummins Unit's execution room for the second time (a last-minute stay meant the execution was delayed) Rosenberg described the moment the curtains opened.
"Marcel Williams's eyes looked right up at the ceiling. He was on a gurney, tied down. His head was locked in place and the right side of his body was facing us, the viewers. He said no final words," Rosenberg wrote.
By the time the curtains opened the intravenous line that drugs would be administered through was already attached. Rosenberg said viewers were not allowed to see it being connected, or given any notification of drugs being administered.
He detailed the moment he believed the controversial drug Midazolam, which the use-by date had prompted the rush of judicial killings, was injected.
"His eyes began to droop and eventually closed (the right one lingered slightly open throughout). His breaths became deep and heavy. His back arched off the gurney as he sucked in air," Rosenberg wrote. "I could not count the number of times his body moved in such a way, rising off the gurney."
As Rosenberg noted, the first injection, a sedative, is meant to ensure there is no movement after five minutes of it being administered.
In the execution of Jack Jones, which preceded Williams' on Monday night, it was claimed by lawyers that the inmate was still moving and "gulping for air" more than five minutes after being injected with the drug.
After hearing from the attorney-general's office, a Supreme Court judge decided that was not the case, and rejected Williams' lawyers appeal for a stay on his execution.
"I was watching him breathe heavily and arch his back and then the breathing began to shallow out," he wrote. "By 10.24pm, Williams looked completely still."
Rosenberg described an obvious consciousness check followed by apparent continual checks by officials touching the prisoner's hands and face, and finally running a finger across his eyelids.
Procedurally, the second drug should have been injected at this point, but Rosenberg writes, even though he was invited to witness the killing, he couldn't see when the drugs were injected or hear if there was any sound.
"I do not know when the second drug, which would mask all pain, was administered. I did not see the IV placed. The audio was cut so I could not hear whether he was moaning, and I could not see how many times each drug was administered - meaning, even as a witness, I could not say if Marcell Williams felt pain or what happened during his death by the Midazolam three-drug protocol," he wrote.
The reporter said he did not believe Williams' death was peaceful.
"Protocol ensures that by the time the potassium chloride, which stops the heart and can be excruciatingly painful, is administered, even if the prisoner feels pain, the viewer will not see it. The paralytic is in place," he wrote.
"Near 10.31pm, they switched off the IVs. The man who had been checking for consciousness pulled out a stethoscope and put it to Williams' heart. He called in a coroner. I remember seeing Williams, there on the gurney, not moving."
Williams's time of death was 10.33pm.
Williams' execution went differently to Jones' hours earlier. Witnesses to the evening's first execution heard his last words - a two-minute statement in which the killer apologised and expressed remorse for the 1993 killing of Debra Reese with a tire iron.
The week before, KATV reporter Marine Glisovic said the execution of Ledell Lee, the first man to be executed in Arkansas since 2005, was quiet.
"He stared up the entire time," she told the New York Times. "As it's going on, it's quiet. No one's saying anything. It was very sterile and clinical. It was like watching somebody being put to sleep, if you will."
The rush of killings in Arkansas has prompted renewed debate and interest in the death penalty.
This week's double death inspired the Times to collate a series of accounts from witnesses to past executions.
In the series of interviews, former Ohio lawyer Charles Coulson described attending two executions at the families' invitations.
He said he was "disgusted" with the process.
"They had a chance to offer last statements, and I was disgusted because they were so self-serving, narcissistic statements for these people who had caused so much pain and suffering," he said.
"It's not like watching a gory murder in a movie. When I watched the executions, I was very impressed with the State of Ohio and how dignified they handled this. In my opinion, these two defendants didn't deserve any dignity whatsoever."
Gayle Gaddis, the mother of a murdered Houston police officer, said she ended up in the viewing room for an execution because she wanted to see her son's killer "finished".
"I went in the room, and I saw him strapped on that gurney. Then I couldn't watch it. They gave me a chair, and I just turned it the other way," she said. "I was hoping he'd say, 'I'm sorry', but he wouldn't even look at us."
A defending lawyer from Phoenix, Jennifer Garcia, said she attended a client's execution because "if he needed reassurance, he'd be able to see one of us smile at him."
"I knew I had to hold it together for him, and I had to make sure he was OK through the process," she said. "Over all, you feel shell-shocked. I wouldn't say I'm necessarily haunted by it, but I'm very aware of it."
As a prison chaplain in Texas, Reverand Caroll Pickett witnessed 95 executions.
"People don't realise that you never get over it, unless you're just cold and calculated. I'll never forget it. Not a day goes by. Not a day goes by. And I don't expect it to," he said.
The state of Arkansas is set to carry out its final execution for the month, that of Kenneth Williams, on Thursday.
