And across the country the debate was rejoined about the prevalence of guns and the urgency, or not, of imposing tougher control.
A murderous Thursday in the bustling financial district of Atlanta had appeared to end with the suicide of Barton after he was stopped by police as he drove through the city's prosperous northern district of Cobb County, just hours after the shooting spree.
Even as he was apprehended, however, police had discovered the bodies of his family, his wife and two children, hammered to death in their home in a southern suburb of the city.
The authorities had also accessed Barton's police record, and unearthed reports about the hacking and beating to death of his former wife and mother-in-law six years before in the neighbouring state of Alabama - a crime that had never been solved.
Attention yesterday though, focused on the discovery of the bodies of his wife and two children at their flat in Stockbridge, and the release by police of a note left in the flat, and signed by Barton. The note made no direct reference to any plans for slaughter in the brokerage houses, but contained an oblique threat to people who, he said, had tried to destroy him. "I don't plan to live very much longer," Barton had written, "just long enough to kill ... the people that greedily sought my destruction."
He said he had killed the children, Matthew aged 11, and Elizabeth Mychelle, aged 8, to spare them the pain of living as orphans. Using a hammer, he said, "just seemed like a polite way to kill and a relatively painless way to die. There was little pain. All of them were dead in less than five minutes."
Police also disclosed that Barton's 27-year-old wife, Leigh Ann, had been killed on Wednesday evening, and her body hidden in a wardrobe to conceal it from the children. They were killed the following day, their bodies placed in the bath before being laid in their beds. A toy was placed on the body of each child.
Twelve people remained in hospital yesterday, seven of them in critical condition, being treated for injuries sustained in the attack on the two brokerage firms, All-Tech Investment Group and Momentum.
It also emerged that not all the dead or injured were shot. Some were hurt in desperate attempts to flee the gunman, who was firing at random across third-floor offices with windows that were sealed.
In the political arena, the shootings at the two brokerage houses prompted a resumption of the furious debate on gun control that had erupted after the multiple killings at Columbine High School in Colorado in April. President Clinton, who was in Sarajevo for the international conference on rebuilding Kosovo, issued a brief statement expressing his sorrow at this latest outbreak of shooting violence in America. Vice-President Al Gore was quick to offer the Atlanta authorities all the federal resources they might need in their investigation.
Both Mr Clinton and Mr Gore have been staunch supporters of stricter gun controls and Mr Gore last month cast the deciding vote in a tied Senate to approve additional checks on gun-purchasers.
The following week, however, the House of Representatives rejected new legislation after intensive lobbying by the National Rifle Association and congressmen representing mainly rural constituencies in the South, where the Second Amendment of the Constitution, the right to bear arms, is interpreted as a licence to carry all varieties of guns for personal defence as well as hunting.
Yesterday, Representative Nita Lowey, a Democrat from New York, said that the Atlanta tragedy "highlights once again how important it is that we enact meaningful gun safety legislation. The American people are demanding action."
A number of yesterday's US newspapers, however, did their utmost to bring gun control back into the forefront of national concern. "Latest senseless slaughter screams for serious gun debate," said the lead editorial in USA Today, the American newspaper that comes closest to being a national daily.
It was not clear, the paper said, how Barton had obtained his weapons, but the point is that more innocent people are gun-dead.
"And, as their names are added to the list of gun victims that will total 30,000 or more by year's end by accident or intent, it is possible to understand the growing public unrest with the failure of lawmakers to enact unified, comprehensive controls. This is a public-safety issue."
On the Internet, however, opinion was more evenly represented, with many contributors arguing for more guns rather than less.
If only one person in that office block had had a gun and opened fire on the killer, they insisted, fewer people would have lost their lives.
Even before the Atlanta shootings, the gun-control issue was already edging its way back into Congress. Yesterday the House was expected to name its members of a special committee being formed to consider firearms legislation with a view to getting the Bill rejected by the House last month on to the statute book in some form or other by autumn.