A Ret. Bomb Technician Explains Package Bombs and Trip Wires Used in Austin Bombings

For nearly three weeks in March 2018, the city of Austin, Texas, was terrorized by a serial bomber. Suspect Mark Conditt, a 23-year-old Texas native, allegedly detonated five package bombs—killing two and injuring five others—before he killed himself by detonating an explosive inside his own vehicle when he was cornered by SWAT team members.

According to police, Conditt left behind a 25-minute recorded confession, but he did not explain his motive. He didn't mention an affiliation with a terror group or whether his attacks were racially or religiously motivated.

To better understand package bombs and the serial bombers who employ them, we spoke with Tina Sherrow, a retired bomb technician and certified explosives specialist for the Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF).  During her time with the ATF, Sherrow investigated dozens of bombing cases, including six serial bombers.

It seems like the perpetrator tried to use FedEx to send some of his bombs. The Unabomber, Ted Kaczynski, sent his bombs by U.S. Postal Service. How common is it for bombers to try to send bombs through the mail?

It's rare, but it happens. It's difficult to build something that you know is going to survive the rigors of going through the mail. It takes a little more of an advanced skill level to create.

Watch: Naomi Ekperigin takes a look at the life of Ted Kacynski, aka the Unabomber, including his early admission to Harvard at 16 and his final break from society.

How might someone know, without opening it, that a package contains a bomb?

There might be no return address, oily stains, wires protruding. Then there's the weight: if it feels kind of lop-sided. It's also possible that the explosive material will smell funny and emit an odor through the seams of the box.

Do mail bombs require sophistication to create?

I wouldn't say "sophistication." If you know anything about basic circuitry or know how to build things or are mechanically inclined, this is not terribly difficult to do. It's…someone who has taken more time than the average guy who sets a pipe bomb out there.

We have bomb technicians in the military who deal with far more advanced technology than this.

Does this case remind you of any others you've worked on?

It's most reminiscent to me of the Eric Rudolph case—[he bombed] the Centennial Olympic Park (in Atlanta, Georgia) in '96, the Otherside Lounge (also in Atlanta) and then the Birmingham device (where he bombed an abortion clinic in Birmingham, Alabama).

It's reminiscent because of the terror he inflicted on the city of Atlanta. Our leads were few and far between…and we didn't know his motive until he started sending his letters and messages.

While they weren't package bombs, per se, they were just concealed in different types of containers.

Those were more advanced [than the Austin bombings] because they were mechanically timed.

As opposed to?

With Austin, it sounds like they were all victim-operated devices. Even the one with the trip wire.

Why are timed bombs considered more advanced than one that's victim-operated?

I have no idea what the components were in Austin, but it seems like these were place-and-go, without a timing mechanism. Sometimes anti-disturbance devices like that are dangerous for the bomb technician in that you can't bump it…but the Eric Rudolph devices were different in that you didn't know if you had a 12-hour window or 30 seconds.

The trip wire that the Austin bomber used sure sounded pretty sophisticated.

The element that's more diabolical about the trip wire is that we consider it a booby trap. It's not that much more difficult to employ, it's just another step into the design that the bomber has made. While to the layperson it sounds like something very different, it was just a different means of opening the package.

Whenever there's a serial bomber on the loose, a lot of people tend to assume that the perpetrator is some kind of terrorist, motivated by an extremist political agenda. In your experience, have you found that to be true?

It's a misconception. We as human beings naturally try to mind-read and jump to conclusions, but with every bombing case I've ever worked, it's a different motive every time: revenge, love triangles, an ex-wife's new boyfriend.

Mickey Antonelli was a serial bomber… He didn't like that [his ex-wife] had a new boyfriend. The first device was the intended target. The second device was a completely random person. The third one...took place in a completely different place.

The Danville [Illinois] Church bombings had something to do with [the perpetrator's] brother being paralyzed when he was younger.

The Hammond, Indiana serial bombings in the early '90s were police officers using the devices as distractions in one area of town while they committed burglaries in another area of town while law enforcement was preoccupied.

What about race-related bombings? The first victims in the Austin bombings were Black, leading to speculation about this being a hate crime. Have you investigated many hate crime bombings?

I've investigated dozens of bombings and hundreds of explosions. In my years of working, I don't recall any bombing investigations that were hate crimes, with one exception: a commercial firework that somebody placed into a Middle Eastern family's van.

What do you think is the biggest misconception people have about serial bombers?

It's easier to do than people think it is. We're very fortunate in the United States that it doesn't happen more. But law enforcement has definitely learned lessons over the years from Eric Rudolph-type bombings to be better than we were years ago.

It seems like there's a lot of secrecy on the part of law enforcement about what's in these bombs.

We can't release information on the devices to preserve the integrity of the investigation, and I know that's hard for people. They want to know. But the reality is, knowing the details of the device isn't going to make you any safer.