SAN ANTONIO - A retired FBI leader and bomb technician believes the person behind the serial bombings in Texas is a professional, not a novice.
The fifth and sixth package bombs were found Tuesday, one of them in Schertz.
Details of the investigation are being watched closely by Danny Defenbauch, who spent almost 33 years with the FBI. He was the lead investigator in the Oklahoma City bombings after traveling to 25 countries, countering terrorism.
To Defenbach, one thing has become increasingly clear.
"I would be willing to say that you won't be able to see something like this being learned on YouTube," he said.
Defenbach knows identifying the person or people building the bombs hasn't been easy for many reasons.
"The bomber doesn't seem to care who the victims are. So you have no identified specific target," he said.
In these cases, Defenbach said, the story can lie in the bombs themselves.
"From those construction techniques, the way the wires are twisted, the way the connections are insulated, many times can be a very specific clue as to the expertise of the bomb builder," he explained.
Defenbach expects that local, state, federal and even military investigators are focused on the "signature construction technique."
When asked why the bomber doesn't just change that technique, Defenbach said: "The last thing the bomb builder wants to do is kill himself. Therefore, if you manufacture it and use the same ways every time, it raises the element of safety for the bomb builder. You've got to be pretty meticulous or you can blow yourself up."
Defenbach has investigated many serial bombings and said while other people may be involved in this case, there is typically only one person making the devices.
"Usually, the bomb builder, that characteristic or that knowledge, and expertise would usually be single source," he said.
Defenbach praised law enforcement for acting quickly and keeping details about the bombs to themselves to ensure public safety.
"I'm praying for them," he said. "They gotta get this solved fast."
Defenbaugh said the best evidence is a bomb that has not yet exploded, which would allow investigators to pick apart how it was made.
That is one reason law enforcement is asking anyone who sees anything suspicious to call 911 before they touch it.
Bexar County Fire Marshal Chris Lopez reminds residents of possible indicators of package bombs:
- Unexpected or unknown packages
- Lack of a return address
- Excessive postage
- Packages marked "Personal" or "Private"
- Packages containing an irregular shape or surface
- Packages with excessive tape or protruding wires
- Packages with unusual markings, stains, spots or emitting unusual odors
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