DALLAS (CBSDFW.COM) - When it was hard to imagine how the scene in downtown Dallas Thursday night could be any more chaotic, up on the second floor of a parking garage the suspected shooter, Micah Johnson, told a hostage negotiator there was more to come.
"The suspect stated we will eventually find IEDs," Dallas Police Chief David Brown said at a news conference.
ATF (Bureau of Alcohol, Tobacco, Firearms, and Explosives) agents were soon on scene and a pair of highly trained explosive detection canines went to work.
For the next six hours, the two dogs sniffed for bombs.
While nothing was found, the work of the ATF to help piece together what had just happened on the street of Dallas had just begun.
Senior Special ATF Agent Nicole Strong said the amount of evidence and the size of the crime scene will make the investigation time consuming and challenging.
She said, "If you can picture a jigsaw puzzle in a box and you take the lid off, drop it, and all the pieces scatter to the floor - that's how hard it is to put this together,"
The ATF's explosive detection canines were also sent to Johnson's home in Mesquite where bomb-making materials along with guns and ammunition were found inside.
ATF agents are working to trace the guns and ammunition to find out where and when Johnson purchased them.
"It's a huge piece of the puzzle," Strong said. "What if that gun was purchased 12 hours versus 12 years before the shooting. That may give us some insight into the motivation of the shooter."
Shell casings collected at the downtown crime scene will also eventually be turned over to the ATF so the federal agency can cross-reference them with a national crime database.
"We may be able to go back and link them to other crimes scene in the past and possibly clear up other crimes," Strong said. "We want to get every piece to bed so we can close this and get it right."
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