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 while he dropped off two explosive packages that allowed them to conclusively know who their suspect was.

Surveillance photos appear to show the suspect inside the FedEx shipping store on Brodie Lane. The pictures show a timestamp of March 18, 2018 at 7:37 p.m. The suspect, who seems to have blonde hair, is wearing a baseball cap and can be seen carrying two packages. His hands appear to have gloves on them.

“His fatal mistake was when he walked into the FedEx office to mail the package because from there we can get surveillance video of him, of his vehicle and license plate number, identify the individual and at Home Depot where he bought the stuff and with the cell phone to locate him, which they did this morning,” says Rep. Michael Michael.

McCaul who is chairman of the House Homeland Security Committee, confirms Conditt “brought a lot of his bomb-making equipment through The Home Depot in Pflugerville, close to his home. He did have a battery pack and he had nails.” That Home Depot location is inside Pflugerville’s Stone Hill Town Center.

KXAN Investigator Jody Barr spoke with a Home Depot manager named Chris—who would not give his last name—at the Pflugerville location Wednesday afternoon. The manager said law enforcement told store employees to not discuss any details related to investigators’ work regarding Conditt’s purchases at the store.

McCaul said Austin Police Chief Brian Manley told him the suspect also had a list of addresses on his computer of where he placed or mailed the bombs. 

Employment-related searches reveal Conditt, 23, worked previously as a computer repairman and also listed him as most-recently working for Crux Manufacturing, a Pflugerville robotics and mechanical company. Crux’s website shows it specializes in “exotic” materials.

• MORE: What we know about the serial bomber

KXAN investigators spoke with both the owner and another worker at Cruz, asking for confirmation of Conditt’s employment there and whether he was fired last fall. They both declined, saying they would have to check with law enforcement before commenting further.

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.

At this time, police have yet to provide a motive, but they have revealed some details about how the suspect’s method.

A federal criminal complaint and arrest warrant against Conditt was filed late Tuesday night.