AUSTIN -- (KXAN) -- NBC News is reporting that the bomber used a foreign and “exotic” battery in each of his explosives, multiple senior law enforcement officials briefed on the investigation say.
As one law enforcement official put it, "these weren't your store-bought Duracells."
Multiple officials say the batteries were ordered online and one senior law enforcement official says they came from Asia.
It was this signature trait that allowed investigators to so quickly link the various explosions to the same man.
In addition, as NBC News first reported yesterday, the FBI was able to come up with a list of phone numbers and individuals that were in the area of the bombings when they occurred using cell-site analysis and high-tech computing systems that can find patterns of callers in certain areas.
Lastly, multiple law enforcement officials say it was the suspect being captured on video surveillance yesterday while he dropped off two explosive packages that allowed them to conclusively know who their suspect was.
Two senior law enforcement officials say hours before police tried to pull the suspect over in his car, he turned on his cell phone. This alerted police to his location and they were able to start following him, ultimately bringing the case to its conclusion when the suspect blew himself up in the car.