The bombing was declared a terrorist attack by the Federal Bureau of Investigations, which took instant control of the inquiry. It was also quickly determined that the blast was caused by one or more small pipe bombs deposited in a bag amid a crowd attending a late-night rock concert in the park.
Officials confirmed that an emergency call was placed to the Atlanta police 18 minutes prior to the explosion from a public telephone two blocks away. The call could offer further leads to the investigators. Initial reports suggested that the caller was a male with an American accent.
Before dispatchers were able to relay the warning to police at the concert, an officer had been alerted to the presence of the unattended bag and had begun dispersing people when it detonated. Given the length of the warning period, questions were being asked why it had not been possible for the police to act faster to clear the area.
The greatest break in the investigation could come from a recording of the concert by one of the US networks or even from the still photographs of a spectator. Under the best scenario, the person may even have been captured on film placing the bag containing the explosives in the crowd.
The use of a pipe bomb, a crude device that can be assembled by almost anyone, pointed away from a foreign terrorist organisation, which would be expected to have used more sophisticated means, and towards either a crazed individual or, more ominously, an American militia group.
Echoing through the investigation was the arrest in April in Macon, an hour south of Atlanta, of three members of a militia group calling itself the 112th Regiment, Militia-at-Large for the Republic of Georgia. The men face charges of conspiring to make pipe bombs and other explosives and weapons for a campaign against the government.
The phenomenon of renegade militia groups has taken a high profile in the US in recent months, in particular in the wake of the Oklahoma City bombing which killed 168 people last year.
Until the downing of TWA 800 10 days ago, it was the second most deadly terrorist attack on American citizens - 189 US nationals died at Lockerbie. On 1 July, meanwhile, police arrested 12 members of the so-called Viper Militia at a secret training ground in the Arizona desert.
A second scenario, however, would point to an attack by a deranged person working alone. A little-recorded incident at the Los Angeles Olympics in 1984 involved the arrest of a single man, armed with several home-made pipe bombs, who was caught tailing a bus of athletes.
The simplicity of making a pipe bomb was underscored by Jeff Beatty, a security consultant and a former FBI agent. "It's not difficult. The material is pretty much available in any plumbing store," he said yesterday.Reuse content