A Catholic priest who has witnessed 18 executions has spoken about the one that has always stayed with him.
Reverend Dale Recinella has seen his fair share of state-ordered killings during his time as a death row chaplain in the USA but says that his mind always returns to Angel Diaz.
Diaz was a convicted murderer, but didn't deserve what happened to him when his death sentence was carried out.
A botched lethal injection had him writhing in agony for 34 minutes, more than twice the time that the whole procedure is supposed to last.
Diaz was clearly in extreme pain during the whole thing and his skin began to turn black and fall off - exposing pink flesh beneath - as he suffered from horrendous chemical burns.
It's enough to make anyone speak out against the death penalty.
Reverend Recinella is an anti-execution campaigner but agrees to support the inmates through their final moments in order to comfort them as they are executed.
Brave stuff.
The 67-year-old became a priest after enduring a life-changing brush with death that turned him from a 'money grubbing' lawyer, by his own admission, into a force for good.
He often gets to know the inmate for many years - sometimes as many as 15 or 20 - before they are eventually killed. That must make watching them die on a hospital gurney even more traumatic for him.
He says that the inmates he tries to save often see him as a father or brother figure.
Mr Recinella told Mirror Online: "When you've known somebody for that long you've allowed yourself to really care about him like a brother, like family.
"I've had guys hug me in the death house and say 'you're the father I never had', 'you're the brother I never had'.
"'If I had a friend like you on the other side I never would have come here'.
"And then you go and watch them be killed. It's not a healthy thing.
"It's better for me to be there than not be there.
"That's what I am there for, to become family.
"I've had to learn to deal with my trauma from watching people I love be killed."
As one of the few people allowed to witness executions in the death houses of US prisons, Mr Recinella has to visit a grief counsellor for his own mental health.
He continued: "It stinks to high heaven because it is so depressing.
"They don't believe there's anything on the other side of the line. That's rough. I believe there is.
"I'm not going to do any man any good by adding to the depression.
"I've got to prepare myself to go in there and bring something that is going to make his day better.
"I can come in and try to help him find a way to keep his spirits up, to focus on the things in his life that are good and really matter to him, and to keep his world bigger than [a cell measuring] six feet by nine feet."
The reverend's job sees him spend between 40 and 60 hours each week behind prison walls in Florida. Many inmates spend years on death row, but then - once their warrant is signed by the state governor - they head to the death house.
Of Diaz's execution, he said: "I have never witnessed an execution by electric chair, thank the Lord.
"But I have witnessed a botched lethal injection and what I found out is there is not much difference between burning a human being to death alive from the outside in with electricity than burning a human being to death from the inside out with chemicals.
"I testified in a court case to try and ban executions in Florida because of what Angel suffered during the last 34 minutes of his life."
Recinella got the job, for which he isn't paid, after the brutality became too much for his predecessor.
He continued: "The priest that was doing this before me for 15 years had witnessed four electrocutions and in the last one in 1997 the man caught on fire in the chair and burned to death, screaming with flames jumping three feet out of his head.
"And that priest, who was an incredibly spiritual man, his health broke and he told the bishops 'I can't do this anymore'."
He rightly described his job as "the most demanding volunteer role in the world".
As you can probably imagine, 'Brother Recinella' - who has met Pope Francis as part of his work against the death penalty - wishes that America would scrap the whole thing.
Of watching an execution, he added: I can't let myself feel anything. I get out to the parking lot and I get home and it usually takes hours to remove all the concrete steel I had to put around me to keep any feelings from coming out.
"And then it starts coming. You have to process it. That's what the grief therapy is for, to uncork all of that.
"The feelings are 'holy Toledo, why are we doing that [to inmates]?'"
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