ATLANTA - The armed barricades and daily bomb scares of last summer long have faded into memory, but - psychologically, at least; just beneath the surface - Atlanta remains very much a city under siege.
Four pipe bombs have exploded at three different locations here since July, striking targets as disparate as an outdoor concert, an abortion clinic and a lesbian-owned nightclub. And the FBI is warning minority communities that they could be targeted next should the perpetrators strike again.
"I've never been to the Middle East, but from what I've read I imagine that this is what it's like," said Kay Scott, executive director of Planned Parenthood of Atlanta. "You take the best precautions you can, but you've got to get on with your life."
The FBI did little to ease the jitteriness Thursday with an appeal to the public for help in solving the cases - the third such appeal since the first bomb exploded July 27. Authorities all but acknowledged that they are nowhere near to making an arrest or determining whether the bombings are related.
FBI Special Agent Woody Johnson struck a positive note. "We're making progress every day," he said. But then he used a metaphor that the FBI also used at one point in the unsolved mystery of the explosion of TWA Flight 800. "I see this thing very much like a thousand-piece puzzle. We're steadily filling it all in."
Authorities released grainy photographs of eight people and a sketch of a ninth man who were in Centennial Olympic Park before a pipe bomb exploded during the 1996 Olympics, and asked for help in making identifications.
"We are asking the depicted individuals to promptly contact the FBI and we also are seeking help from the public to aid the FBI in identifying and locating these nine persons," said Johnson.
Johnson stressed that they are not suspects. Agents want to interview the nine people because they were near the site of the bomb shortly before it exploded and might have useful information, he said. One woman was killed and more than 100 people were injured by the bomb. In addition, a man died of a heart attack connected to the bombing.
Despite strong similarities between the last two bombings - both involved twin devices, timed to go off in such a way as to injure or kill law enforcement personnel - there also are enough differences that authorities can't yet say with certainty whether they are related.
"We could be dealing with three different individuals in this thing," Johnson said.
While investigators are looking into the possibility that the bomber or bombers have a militia or military background and may harbor a hatred of law enforcement or government, Johnson said investigators may not be able to determine whether the bombings are related until they can zero in on a suspect.
Nor were agents able to answer the question on the minds of everyone here: Why Atlanta?
Indeed, while city residents seem to curtail few activities because of concern over terrorism, a lingering residue of fear may be Atlanta's dominant legacy of the Summer Olympics. Once known as the city too busy to hate, Atlanta has in recent weeks had to cope with the possibility that a hateful and deadly serial bomber is stalking its streets.
In an indication of how jittery the city is, authorities only Monday shut down a major highway for an hour and a half during rush hour because someone spotted a suspicious object on the median. It turned out to be a college student's lost backpack containing school books, some food and deodorant.
Building evacuations still occur with some frequency because of phoned-in bomb threats. "Some really sick people are out there having a field day because they have the power to empty buildings," said a member of an organization that has received harassing phone calls but who did not want to be identified. "You can't ignore it."
FBI officials said they have been meeting with local law enforcement personnel about taking precautions during next month's annual weekend college spring-break street party known as Freaknik, which is expected to attract more than 100,000 black college students. The event falls on the fourth anniversary of the federal assault on the Branch Davidian compound in Waco, Texas, and the second anniversary of the Oklahoma City bombing.
Federal agents are sifting through evidence in the bombings.
"In the Olympic bombing investigation, we have interviewed more than 2,000 witnesses, cataloged and reviewed nearly 1,000 videotapes and 5,000 photographs, and completed more than 7,000 investigative and forensic reports," Johnson said.
Through interviews and painstaking cross-matching of photographs and videotapes, he said they've been able to identify hundreds of people who were near the bomb site.
A dark-haired white man depicted in the FBI sketch - and believed to be in his 20s, between 5-feet-8 and 6 feet tall and between 140 and 170 pounds - was seen by witnesses sitting on the bench where the bomb was placed, authorities said.
Here is a description of the four photos and a sketch showing nine people whomthe FBI seeks to identify and question in the Olympic Park bombing: