"For all intents and purposes, I think this case has been concluded," said Jimmy Mercer, the Atlanta police chief, yesterday morning, his voice still shaking from reading out the letters.
But the shock of Barton's killings will not quickly dissipate. Nor will the disbelief. One more time, a prosperous community in America is coping with a bloody tragedy that has left 13 dead, including Barton himself, and 20 injured.
The death trail began slowly and deliberately at the suburban apartment he had taken with his second wife, from whom he was estranged, and the two children from his first marriage. They were his first victims. But it ended in a mad and terrifying massacre on Thursday afternoon at the offices of two stocks and shares day-trading businesses on a gleaming business campus in Buckhead, a northern suburb of Atlanta. In a spray of bullets from the guns he held in each hand, he killed nine people, before fleeing and later committing suicide.
What he left behind was one of the worst killing sprees in America's history and the bloodiest ever in the city of Atlanta. Also - another first - an apparent stock market driven massacre.
It left a tangle of questions and concerns. In particular about the pressures of "day-trading" on the stock exchange - a very mid-Nineties world, born of Internet technology and the bull market, to which Barton, we know, was deeply devoted. On Tuesday, a cheque he wrote for $50,000 to cover stock exchange losses bounced. He recently took a loss of at least $80,000.
Barton might have been the quintessential, boring suburbanite. He was known for his broad smile but a private demeanour. He was a former Scoutmaster. This week, he had promised to buy his son a lizard so he could earn his Cub Scouts' reptiles badge. But there was something else not boring about Barton: in 1993, his first wife and her mother were hacked and beaten to death in a camping resort in Alabama. Barton was there and was the prime suspect. But charges were never brought.
Barton always asserted his innocence in those murders. This week, he did so again in the first letter found by investigators at his apartment. "There is no reason ... to lie now," he wrote. But he was responsible for the unspeakable scene that awaited the police officers in the humble two-bedroom unit. He directed them to the bodies, told them how he had killed them. And, again, he tried to explain why.
First, on Tuesday night, after she was asleep, he bludgeoned his wife, Leigh Ann. He wrapped the body in a blanket and stuffed it in a cupboard. He waited until Wednesday night to do the same to the two children, Matthew, 11, and Mychelle, 7. He left them under blankets on their small beds.
"There was little pain," he wrote of killing his family. "All of them were dead in less than five minutes. I hit them with the hammer in their sleep and them put them face down in the bathtub to make sure they did not wake up in pain. To make sure they were dead. I'm sorry. I wish I didn't. Words cannot tell the agony. Why did I?"
Barton's letter continued: "I have been dying since October. Wake up at nights so afraid, so terrified that I couldn't be that afraid while awake. It has taken its toll. I have come to hate this life in this system of things. I have come to have no hope. I killed the children to exchange them for five minutes of pain for a lifetime of pain. I forced myself to do it to keep them from suffering so much later ... The fears of the father are transferred to the son. It was my father to me and from me to my son. He already had it."
In addition to the longer letter, Barton left a short note with each of the bodies, expressing his love for them. He said he hoped to meet them in the after-life.
Reading them yesterday, Mr Mercer could not hold back his own tears, and reporters were also sobbing.
Of Leigh Ann, from whom he was separating, Barton said he killed her because she was "one of the main reasons for my demise".
There was nothing to explain, however, what drove Barton to take the bloodshed so much further on Thursday. He arrived at the All-Tech Investment Group shortly after 2 pm, where he was heard to observe that it was a bad trading day (the New York stock market was indeed plummeting) and that "it was going to get worse". Shortly before 3pm he opened fire. First he shot the manager and his secretaries before turning his weapons on the clients who were in to do their instant trades. Someone heard him exclaim: "I hope I'm not upsetting your trading day". In all, four died in the office.
Barton then fled across busy Piedmont Road to another four-floor office building and the offices of Momentum Securities where had also been a client. There, he continued the carnage, killing five more and wounding several others. Officials yesterday said three of those hurt remained in critical condition.
For Atlanta, it was another gruesome intrusion into high summer. In July alone, it has watched in shock as 23 of its citizens have died in mass killings. The worst incident, before this week, occurred on 12 July, when police found three adults, including the gunman, and three children shot dead in a family house in the city.
Still we do not know the precise nature of the depression that Barton said was afflicting him. It may have stemmed from the killings of his former wife and mother-in-law. Speculation yesterday continued to centre on his passion for day-trading, not least because it was the offices of two companies that specialise in the industry that he had chosen for his final assaults.
Day-trading can be a heady combination of video-poker and serious investing. Its practioners play the markets minute by minute, shuffling stock holdings when they shift in price by just a few cents in a bid to accumulate profits. The industry, of which All-Tech was a pioneer, has attracted about 5,000 users across the US, some of whom do it from home and others in offices like the ones that became bloodbaths on Thursday. Experts have long warned that it is a risky pastime that can bring large losses and generate huge stress.
For a few desperate hours the authorities had no idea of Barton's whereabouts. In his letter to detectives, he asks that they catch him and kill him. But that was not necessary. At 7.45pm a police patrol car spotted his green Ford van in a town to the north-west of Atlanta and pulled it over into a petrol station. When they approached it, they saw that Barton had already killed himself.
A bunch of flowers lay outside the offices of Momentum Securities yesterday. The note said: "I'm so very sorry". So, apparently, was Barton. And so, yesterday, was Atlanta and all of the United States.
The Killer's Words
The text of a note found in Mark Barton's apartment along with the bodies of his wife, son and daughter.
July 29, 1999, 6.38am
To Whom It May Concern,
Leigh Ann is in the master bedroom closet under a blanket. I killed her on Tuesday night. I killed Matthew and Mychelle Wednesday night.There may be similarities between these deaths and the death of my first wife, Debra Spivey. However, I deny killing her and her mother. There's no reason for me to lie now. It just seemed like a quiet way to kill and a relatively painless way to die.
There was little pain. All of them were dead in less than five minutes. I hit them with a hammer in their sleep and then put them face down in a bathtub to make sure they did not wake up in pain. To make sure they were dead. I am so sorry. I wish I didn't. Words cannot tell the agony. Why did I?
I have been dying since October. I wake up at night so afraid, so terrified that I couldn't be that afraid while awake. It has taken its toll. I have come to hate this life and this system of things. I have come to have no hope.
I killed the children to exchange them for five minutes of pain for a lifetime of pain. I forced myself to do it to keep them from suffering so much later. No mother, no father, no relatives. The fears of the father are transferred to the son. It was from my father to me and from me to my son. He already had it and now to be left alone. I had to take him with me.
I killed Leigh Ann because she was one of the main reasons for my demise as I planned to kill the others. I really wish I hadn't killed her now. She really couldn't help it and I love her so much anyway. I know that Jehovah will take care of all of them in the next life. I'm sure the details don't matter. There is no excuse, no good reason. I am sure no one would understand. If they could, I wouldn't want them to. I just write these things to say why.
Please know that I love Leigh Ann, Matthew and Mychelle with all of my heart. If Jehovah is willing, I would like to see all of them again in the resurrection, to have a second chance. I don't plan to live very much longer, just long enough to kill as many of the people that greedily sought my destruction.
You should kill me if you can.
Mark O Barton