O'Reilly -- who retired Monday from the Texas Department of Criminal Justice Huntsville Unit, where he presided over more lethal injections than any other warden -- leaves with no reservations, no nightmares.
"I don't have any intentions of changing my mind, reflecting on how could I have ever done this stuff," he said of the execution duty, which began for him in September 2004 when he took over the more than century-and-a-half-old 1,700-inmate penitentiary in downtown Huntsville. "If you think it's a terrible thing, you shouldn't be doing it in the first place. You don't do 140 executions and then all of a sudden think this was a bad thing."
O'Reilly, who turns 60 Wednesday, retired after more than 33 years with the Texas prison agency. On his last day, he looked like a warden from a Hollywood casting call: burly, white-haired, jeans, a western-style belt with a star dominating his buckle, a black shirt.
He didn't keep an exact tally of the number of inmates he stood over as they were strapped to the gurney and prepared for injection. The 140 inmates whose executions he estimated he oversaw account for about a third of the 463 put to death since Texas resumed carrying out of capital punishment in 1982.
Some did leave an impression, although the only name that came immediately to mind for O'Reilly was Frances Newton, who in 2005 became the third woman executed in Texas in modern times. She was the only woman executed under O'Reilly's watch.
"One guy, he cracked jokes, he cracked jokes through the whole thing," O'Reilly said. "I can't remember his name. But I remember things like that."
While O'Reilly recalls the professionalism everyone shows throughout the process, it's the last words of the inmate that tend to draw considerable attention.
With witnesses assembled and looking through windows, the chaplain normally offering a comforting hand resting on the inmate's leg and the final OK from a prison department executive, O'Reilly, standing near the prone inmate's head, leaned over.
"I ask them: Do you wish to make a statement?" he said. "I leave the words 'last' out, or 'final,' or anything like that. I think that's probably better than making a last statement, or final word. I just try to keep that out of it."
The condemned inmates arrive in Huntsville from death row, at a prison about 45 miles to the east, early in the afternoon on the day of an execution. The punishments generally occur just past 6 p.m.
O'Reilly would meet with inmates when they arrived to explain what would happen.
"What I want to do is talk to him and figure out his demeanor," he said. "Whenever they get here, they're either angry, extremely upset or nervous. They know why they're here. ... It's weighing kind of heavy on them. One way or another, it's weighing heavy on everyone here.
"I tell them I want to afford them all the dignity they allow us to. I tell them I'm going to come back at 6 o'clock and tell them: 'It's time."'
Few condemned inmates balked when the "time" arrived, O'Reilly said.
"We've had some tell us: 'I'm not going to fight, but I'm not going to walk,"' he said. "We picked them up and carried them. Ninety-nine percent of them, they walked on their own."
He told inmates they could say whatever they wanted in their last statement, but it must be in English -- "That's all I understand," he said -- and it can't be profane. If the obscenities start, so do the drugs.
"He's got about 15 seconds to do all the cussing he wants to and it will be all over," O'Reilly said. "It is going to be the last thing they're going to say. It ought to mean something. Most of the statements are pretty decent. They apologize to the victim's family and tell their family they love them."
Once the statement is complete, the drugs begin, normally carried through needles inserted in each arm of the prisoner. About five minutes later, a physician is summoned to make the death pronouncement.
The Huntsville Unit was the 11th stop in a career that took O'Reilly to prisons from one end of Texas to the other beginning in January 1977.
Edward Smith, a warden who worked as an assistant under O'Reilly, called him "a natural leader."
"I took from him on how to be cool in the face of crisis, being the warden everyone looks to see if you're in control. And it gives them comfort and confidence to see that ... being committed to the responsibility that comes with being a warden, not consumed by its authority," Smith said.
Although he has no qualms about capital punishment, O'Reilly would prefer to remembered for other aspects of his career. He figures he's worked with about three generations of prison staff and sees some of the grandchildren of people who were there when he started.
"The things I want to stand out in my career, my past, isn't executions," he said.