That pattern-based technology, used by the FBI’s cellular analysis survey teams, gave investigators the ability to identify mobile phones near the blast sites. Zeroing in on devices that showed up repeatedly, they came up with a list of phone numbers of people who were in the area of the bombings, senior federal law enforcement officials said.
Greg Carl, the former director of the FBI's Terrorist Explosive Device Analytical Center, where improvised explosive devices from war zones and American streets are examined, said the Austin investigation appeared to be “textbook” in the use of hundreds of agents, in labs, at computers and in the streets.
“You’re pulling large amounts of data and then going through it, like finding a needle in a haystack,” Carl said. "That’s where it comes down to old-fashioned police work.”
Finally, investigators examining surveillance footage at FedEx centers saw a man drop off two packages, one of which later exploded at the FedEx facility near San Antonio, several law enforcement officials said. Footage shared with the public showed the man, believed to be Conditt, wearing gloves and a blonde wig.
While the high-tech investigations unfolded, agents and police officers were doing the shoe-leather detective work also typical in serial bombing cases: canvassing neighborhoods where the bombs were delivered, talking to witnesses, sifting through tips from the public and hundreds of reports of suspicious packages.
“It’s nice to see that it was good old-fashioned hard work and dedication that resolved this and not theories and psychological profiles,” said Max Noel, a retired FBI agent who helped track Theodore Kaczynski, known as the Unabomber, who was responsible for string of bombings that killed three people and injured 22 over 17 years before his 1996 arrest.
Conditt’s biggest slip-up was apparently thinking he could drop off a package with a bomb at FedEx, Noel said.
“He almost became arrogant," Noel said. "To think he could get away with doing that by wearing disguises and what have you."
Witnesses told investigators of relevant purchases Conditt had made at stores, Texas Gov. Greg Abbott told KXAN. Witnesses also remembered seeing the man with the wig in the FedEx center, and told investigators about the car he was driving, Abbott said. That drew investigators closer to Conditt.
Investigators tracked the suspect’s car to a Red Roof Inn in the city of Round Rock, authorities said, just north of Austin, and 15 miles from Conditt's hometown, Pflugerville.