While serial bombers are rare, the rapid-fire pace of explosions in Austin this month gave authorities clues to chase a suspect who was organized, sophisticated — and acting faster than in previous high-profile cases.
A 24-year-old suspect in the bombings that killed two people and injured others died in a car explosion early Wednesday as SWAT officers approached him in a hotel parking lot in Round Rock, Texas.
Austin Police Chief Brian Manley said authorities were tipped to the man — identified as Mark Anthony Conditt — about 36 hours before the confrontation. But police don't know the motive for the four bombings since March 2 that investigators had said Tuesday were linked.
Danny Defenbaugh, a former FBI bomb technician who helped supervise more than 150 bombing investigations including the 1995 Oklahoma City attack, said such serial campaigns are unusual and can take years to solve.
Defenbaugh said the devices involved in the explosions — and the range of apparent sophistication — probably had investigators trying to narrow a field of possible suspects who have some formal engineering experience in the military, law enforcement or from other sources.
“That fact that someone could build these devices, including the one with the tripwire mechanism, and not blow himself up, that means something," Defenbaugh said. “That’s why they have hundreds of people working on this."
Weldon Kennedy, a former FBI deputy director, called the Austin serial bombings “highly unusual’’ for the army of federal and local authorities who descended on central Texas to solve the case.
Yet Kennedy said investigators benefited from the recovery of one unexploded device that could provide a multitude of clues — from its engineering to the type of components used in its construction.
Kennedy said authorities also are likely to learn something from the locations where the devices were planted.
“The fact that these explosives appeared to target individuals or were sent through the mail and did not target a crowd of people makes me think that this is an individual and not a group with a particular political leaning or cause,” Kennedy said.
About 500 law enforcement officers are working on the case. Austin police are working with San Antonio and Houston police, the Texas Department of Public Safety, the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives.
Manley said evidence collected from all of the bombings is being sent to the ATF lab in Virginia, where they will be reconstructed to determine any links in materials and methodologies.
“We are clearly dealing with what we expect to be a serial bomber at this point,” Manley said.
Texas Gov. Greg Abbott said the state is committing $265,000 in emergency funding for police and the state bomb response team.
An unusual case
Kirstjen Nielsen, secretary of the Department of Homeland Security, told reporters on Capitol Hill on Tuesday that her department was working with FBI to support the investigation.
Nielson said the case wasn't unprecedented because of previous bombers who mailed explosives. But she said the Texas case is unusual because the explosions have come in a relatively tight geographic area and a faster time frame.
“Not like this, not with packages, not in a geographic limited area and certainly not within this time frame," Nielson said.
The explosion early Tuesday occurred at a FedEx facility near San Antonio, about 60 miles southwest of the capital, while the package sent from Austin to an address in Austin was moving on a conveyor belt. A second bomb was found at the facility that hadn’t exploded, investigators said.
A bombing Sunday injured two men. The trigger was a tripwire along a road that investigators said was more sophisticated than the first three attacks.
The others were each package bombs left on doorsteps. The two people killed were Draylen Mason, 17, on March 12 and Anthony Stephan House, 39, on March 2.
“It would be silly for us not to admit that we suspect it’s related,” said FBI Agent Michelle Lee, a spokeswoman.
More on Austin bombings:
Tracing a bomber
Investigators say tracing a serial bomber to a person working for a specific cause is rare. Examples include Ted Kaczynski, who was known as the Unabomber; Eric Rudolph, who bombed Centennial Olympic Park in Atlanta in 1996 during the Summer Olympic Games, and George Metesky, nicknamed the “mad bomber” while terrorizing New York from 1940 to 1956.
Kaczynski mailed explosives that killed three people and injured 24 during a campaign against modern technology that ran from 1978 to 1995. His FBI nickname, Unabomber, stemmed from early targets at universities and airlines.
The FBI-led task force included the ATF and the U.S. Postal Inspection Service with 150 full-time investigators, analysts and others. They ultimately learned that victims were chosen randomly.
His brother identified Kaczynski to the FBI after recognizing the language in a manifesto that The New York Times and The Washington Post published at the request of Attorney General Janet Reno.
A 1996 indictment charged Kaczynski with killing two people. He was charged with bringing a bomb from remote Montana to Oakland, where he mailed it to an office and the man who opened the package was killed in 1995. Kaczynski also was charged with placing a bomb behind a computer store in Sacramento, where it killed the man who moved it in 1985.
Kaczynski pleaded guilty to all pending charges in 1998 and was sentenced to life in prison without possibility of parole.
Rudolph was sentenced in 2005 to four life sentences for bombings that included the 1996 Olympics in Atlanta. Explosives in a backpack killed one woman and injured more than 100, and a journalist suffered a heart attack rushing to the scene.
Rudolph also acknowledged bombing two gay bars. His final bombing in 1998 was at a women’s health clinic in Birmingham, where he left a box with explosives and shrapnel in bushes near the entrance. An off-duty Birmingham police officer spotted the package, which detonated when he touched it, killing him.
Rudolph set off the bomb from nearby and was tracked down by witnesses who got the license number of his truck. But he fled authorities for five years before being caught and pleading guilty to avoid the death penalty.
Rudolph posted a statement in 2005 describing his motivation for the bombings to oppose global socialism at the Olympics, homosexuality and abortion.
Defenbaugh, citing the Rudolph case, said one reason it took so long to solve was because authorities initially suspected the security guard who found the backpack.
Not easy to solve
Brian Michael Jenkins, an analyst with Rand Corp. who has studied bombings, told NBC News that serial bombers often want to communicate their motivations. But such bombings aren't easy to solve without a message or other events to provide clues, he said.
"This requires reconnaissance," Jenkins told NBC. "This requires target selection. They have to think about building a device that works. They have to build that device. They have to think about delivering that device in a way that enables them to conceal their identity."
Metesky terrorized New York City for years by planting explosives in phone booths, storage lockers and restrooms of public buildings such as Grand Central Terminal, Pennsylvania Station, Radio City Music Hall and the New York Public Library.
He planted at least 33 bombs, including 22 that exploded and injured 15 people.
Metesky had been injured in an accident at the utility company where he worked, but his claim for workers’ compensation was rejected because he filed too late, according to a New York Times story marking an anniversary of the case.
Police tracked down Metesky after he wrote letters to The New York Journal-American newspaper explaining his grievances, with language matching complaints in the utility’s personnel file. Police enlisted a psychiatrist to help them, and the case became one of the earliest examples of criminal profiling.
In court, Metesky was declared a paranoid schizophrenic and sent to a hospital for the criminally insane. He died in a state hospital in 1994.
Contributing: Eliza Collins and John Moritz of the USA TODAY NETWORK