The revelations included records of a state investigation in 1994 into claims that Barton had molested his daughter, then aged two-and-a-half, and the results of a subsequent psychological examination that characterised him as a person "capable of homicidal acts and thoughts". Confirmation also came that in recent weeks Barton had suffered a disastrous reversal of fortune in his day-trading activities.
Meanwhile, the political fall-out from the massacre, the worst in Georgia's history, was starting to accumulate. Members of Congress in Washington vowed to accelerate negotiations for the passage of a new gun-control bill while financial experts predicted the passage soon of new laws to regulate the world of day-trading, where fortunes can be made - and lost - in the time it takes to press a computer key.
Flags were ordered to be flown at half-mast across Georgia yesterday as the first funerals were held for the victims of Barton's killing spree. Portraits of those who were gunned down in the day-trading offices revealed them as mostly middle-class, family people who had joined the select community of day-traders to try to supplement their income while saving time for other hobbies, especially golf.
With his suicide as police pursued him on Thursday night, we are denied any sure understanding of what drove Barton to murder. But this might be seen as the all-American crime of the millennium's end. It was not about drugs, gangs or race, the more familiar ingredients of homicides here. It was about about money, about Wall Street, about pressure and about personal failure. As always, though, it featured guns.
Here are some of the elements: Barton, 44, was a white male in a stunningly prosperous society - especially here in gleaming Atlanta - who was seeing his own world fall apart. His second marriage, to his first victim, Leigh Ann Barton, had disintegrated. He had never escaped suspicion of involvement in the hacking death of his first wife and her mother in a camping ground in Alabama in 1993. And the day-trading that had so captivated him as a channel for his intense energies and as a source of new income had turned against him.
Momentum Securities, where four of the victims were slain on Thursday, has reported to the Securities and Exchange Commission that Barton lost roughly $105,000 during 15 days of securities trading beginning on 9 June. The firm said that Barton had "a propensity for highly volatile Internet stocks". Before opening fire at Momentum and then crossing a busy road to the offices of All-Tech, another day-trading firm he had once frequented, he noted that Wall Street was on a down day and things would get worse.
"There seems to be an epidemic of people snapping," observed Dr Larry Buford, a dentist who has a practice in the building next door to All- Tech. "There are people like that today who have never known what it's like to be at the bottom and when it happens to them, then it's like their life is over."
Barton made no reference to his financial ills in the letters he left for investigators at the home where he bludgeoned Leigh Ann on Tuesday and the two children from his first marriage, Mychelle, eight, and Matthew, 11, on Wednesday. But he did portray boiling anger and righteousness. He planned to live long enough, he wrote, to kill "the people that greedily sought my destruction".
Yesterday scrutiny was focused on the murders in 1993 of Barton's first wife and her mother, Debra Spivey Barton and Eloise Powell Spivey. Alabama detectives have confirmed that Barton was always their prime suspect. Just before the deaths, Barton had taken out a $600,000 life insurance policy on his wife. "He was the number one suspect all the way through and still is," District Attorney Richard Igou said. But police could never place Barton in the campsite at the time of those murders.
The psychological evaluation came a year later when suspicions were raised that Barton may have molested Mychelle. David McDade, a Georgia DA, noted that the results were never formally recorded but that the psychologist reported to him that Barton "was certainly capable of homicidal thought and homicidal action". McDade said the reports "make me shudder to this day".
The psychologist, who has not been named, also detected intense anger in Barton about being investigated twice, for the murders and for the suspected abuse. This was the same anger, perhaps, that boiled over in him last week. He apparently complained that police had treated him "like a ghetto nigger". No charges were brought in the child abuse case either.
The Atlanta murders, meanwhile, have shone a spotlight on the day-trading industry as well as on the victims of Barton's rampage. The debate about regulating the business stems from statistics showing that while day-trading can generate fortunes for those who engage in it, it can ruin them too. Ninety per cent of those who try end up losing money, according to statistics. It transpired, meanwhile, that Barton's initial investment on his first day at Momentum Securities cost him no less than $100,000.
Among those who died was Dean Delawella, 52, a native of Pakistan who day-traded to earn extra money for his large family. "He just traded to have money to take care of them and to make a nice home here in America," his brother explained. "This was his dream from the moment he arrived in Atlanta."
The first funeral was held on Friday for Allen Tenenbaum, 48, who owned a food shop and treated day-trading as a hobby beside his other love, golf. He was at the day-trading firm only occasionally. "You can't explain it," said his brother-in-law, Freddy Allen. "It's just a tragic loss for no reason."