Atlanta Bomb Fragments May Help Authorities Piece Together a Case

Littered on the sidewalks of Atlanta’s Centennial Olympic Park, the metal shavings, bits of plastic and torn fiber from last weekend’s fatal explosion at first appeared as innocuous as trash blown from a construction site.

But to the explosives analysts and chemists here and in Washington who have sifted through the powder-singed material in the five days since the bomb blast, the detritus--bent nails, pulverized steel piping and bloody clothing--all have tales to tell, each with a signature leading back to a common suspect.

Explosives experts familiar with the Atlanta bombing say the meticulous process of identifying and retracing the components used in the blast that killed a woman and injured 111 in a crowded downtown plaza will likely take weeks.

But analysts now working to reconstruct the bombs are “pretty confident about this one,” said Robert Holland, a retired Bureau of Alcohol, Tobacco and Firearms explosives expert who is now a private security consultant in Atlanta.

Most of the shredded evidence was shipped last weekend to the FBI’s forensic laboratories in Washington, and analysts said Wednesday that some preliminary findings enabled federal agents to serve a search warrant on the northeast Atlanta apartment of suspect Richard Jewell.

Despite the expected time lag ahead, veteran explosives analysts say that even the crudest, most widely available items--plumber’s pipe, smokeless powder, nails and screws used as shrapnel--have histories that can be narrowed down to their manufacturers.

“Just about every purchased material is traceable up to a point,” said Al Gleason, a Florida security consultant who worked with the ATF and New York City police during a 50-year career as an explosives technician. “You may not get names and addresses, but you can come up with purchases, the name of the manufacturer, even a particular shipment if there’s enough of a paper trail.”

In the Atlanta explosion, the crudeness of the bomb--believed to have been three metal pipes packed with two types of powder, linked to a common kitchen or clock timer and packed into a plastic food container crammed with metal shrapnel--is both an advantage and a handicap to investigators.

While bomb technicians should have little difficulty identifying the makers of the powder, pipes and nails, the sheer commonness of those items means that investigators may have to canvas scores of hardware, home-building and gun stores to run down leads.

“You can narrow it down to the distribution points, but after that it’s all perseverance,” said Holland, a 25-year ATF veteran who headed the bureau’s explosion-and-arson branch in Washington.

Explosives analysts already have one break with the discovery last weekend of a 2-by-3-inch section of metal pipe with its threading still intact. They also reportedly have a usable piece of the torn knapsack that held the bomb.

The piece of pipe could enable investigators to make a quick reconstruction of the bomb’s casing. In some previous instances, pipes have been identified and traced to their manufacturers within a week, Gleason said.

Metal parts can be traced back to particular lots. And if those lots are inventoried properly, they can be linked to certain hardware chains and even individual stores.

Nails, like those packed into the plastic food container of the Atlanta bomb, each have signatures--usually a small mark in the head or shaft that can be traced back to the manufacturer. Steel pipes also have identifying numbers that trace back to their original molds. And each variety of black powder has its own particular characteristics.

“No explosive material is consumed 100% in the process,” said Glen Wilt, a retired Army ordnance expert and president of the International Assn. of Bomb Technicians. “There are always ungrained materials that can be traced back to the manufacturer.”

Investigators retrieved clothing worn by many of those injured in the blast to test the fabric for traces of unburned powder. They also took nails, screws and shaved metal that were surgically removed from victims’ bodies, analysts said.

The decision to send all of the evidence to Washington revived interagency animosities between the FBI and the ATF. Firearms officials in Atlanta had wanted to make a quick comparison between the evidence recovered from Centennial Olympic Park and several unexploded pipe bombs seized during arrests in April and May of three paramilitary extremists accused of plotting to bomb government buildings. But both sets of evidence were ordered sent to Washington.

Despite that friction, several bomb investigators working on the Atlanta case have a long working relationship, officials said. Federal and state explosives experts and retired analysts meet in Atlanta once a month, joining as part of the “Metro bomb group” to discuss current cases and bone up on their science.

Some of the group’s members have worked together since 1990, dating back to the probe of Walter Leroy Moody Jr., a Georgia man whose artfully constructed mail bombs killed a federal judge and a civil rights lawyer in December 1989.

Bomb analysis did not solve the Moody case alone, but the painstaking retracing of the explosives provided direct links to the killer. Agents were able to link grooves on galvanized pipe used in the explosion to Moody’s tool shop and traces of Red Dot smokeless powder back to a purchase at a rural Georgia gun shop.

The major break in that case came when ATF bomb analyst Lloyd Erwin--now working on the Atlanta bomb case--recognized Moody’s lethal 1990 handiwork as being similar to a bomb Moody used to maim his first wife in 1972.

Erwin recognized that in both cases, the bomber constructed his pipe explosive by welding an “end cap” to one end of the metal tube to channel the explosion.

“If you can detect a pattern and you know what you’re looking for, once you get to the store level, you’d be surprised how quick it comes,” Holland said. “You’d be amazed at how well these cashiers and salespeople at hardware stores and warehouses remember their customers.”

Times staff writer Louis Sahagun contributed to this story.

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Investigating a Bombing

Investigators search for and analyze bomb fragments at a bombing site in the same way that murder weapons are searched for at a murder scene. When a pipe bomb detonates, it leaves behind a large amount of fragments as evidence. In Atlanta, The Bureau of Alcohol, Tobacco and Firearms is working with the FBI to reconfigure the device and trace it to the perpetrator. Shown below are the steps involved in a pipe bomb investigation:

* The area is combed for fragments, such as pieces of pipe metal, a detonator or timing device. Once pieced together, a timing device typically provides a telltale signature that can possibly connect the bomb to previous bombings.

* Collected evidence is bagged, tagged and sent to a forensics lab. In this case, fragments collected by ATF are being sent to the FBI’s lab in Washington, D.C. Fragments are pieced together and any explosive residue is analyzed.

* Larger pieces may hold clues such as the brand name of a battery or numbers stamped onto metal.

* Surfaces at the bomb site are swabbed with acetone to detect any explosive residue.

* How the bomb’s components are damaged can tell alot about the bomb. Torn metal usually indicates high-velocity explosives, whereas stretched or deformed metal indicates low-velocity explosives.

* The site is photographed and mapped out, showing where each piece of evidence was found. Investigators use a process called triangulation, where distance between pieces of evidence and from the blast site.

CRATER: The shape and depth of the crater can provide information about the original location of the blast.

Pipe bombs are popular with would-be terrorists because the materials and instructions are readily available. The Internet has long been a repository for crude instructions like the picture a far right, which predates image-based browsers and is done entirely in text Counterterrorism sites also deal with the topic; drawing at right is based on a pipe bomb built by the Unabomber.

Sources: Bureau of Alcohol, Tobacco and Firearms; staff reports

Researched by JULIE SHEER / Los Angeles Times