CSI Britain: Inside the Hunt for Terror Clues

For forensic investigators in the United Kingdom, the race is on to analyze carloads of evidence left in the wake of the attempted bombings in London and Scotland last week. The two unexploded Mercedes found in the capital's entertainment district on Friday were packed with gas canisters and nails as well as hair, fiber and fingerprint clues that can help investigators. In addition, authorities will be able to review the digital data on the cell phones found at the London scene. Police believe these devices were intended to trigger the bomb blasts but failed. Experts say that even the third vehicle involved, a burning Jeep that hit the main terminal at Glasgow's international airport on Saturday, will provide police with a significant amount of evidence, despite the damage caused by the flames. What will investigators be looking for? NEWSWEEK's Susanna Schrobsdorff asked Graham Rankin, an associate professor of forensic science at Marshall University in West Virginia, to explain: Excerpts:

NEWSWEEK: The bombs found in the United Kingdom this week were apparently constructed with some basic materials: gas, nails and a cell-phone device rigged up to act as a trigger. How sophisticated were these devices?
Graham Rankin:
These are probably not sophisticated. They are not using military explosives. They're likely to be made of materials you can readily find. One example is the pipe bomb they found at the 1996 Olympics in Atlanta. The sophisticated part is that it appears that they've rewired cell phones so they can call from anywhere in the world to detonate the device. You'd also find these kinds of devices in Iraq.

How helpful is it to investigators that the cars in London didn't explode?
Of course, unexploded is easier because they don't have to pick up the pieces. They've got intact devices, they can get fingerprints, serial numbers and bar codes to help them trace the parts back to the stores where they were purchased. But they would have been able to find a lot even if it had exploded. Going back to the Oklahoma City bombing [in 1995], they traced the Ryder truck that was used, based on the serial number, or VIN, that was stamped on the axel, and it was really in pieces.

Apparently, investigators used the cell phones that they found in London to locate some of the people that they now have in custody. What else can they learn from the phones?
This is one of those situations like e-mail. People think they've erased a message, but they haven't because if you send a text message or leave a phone message for someone, it's on a computer somewhere other than your phone. Just because you delete it doesn't mean it's gone. So they'll be looking [at] that kind of data in these phones.

Is using a cell phone as a bomb trigger technologically difficult?
I shouldn't really go into detail, but to do it they'd probably be going into the inner workings of the phone so that there's an electrical current, something that would make the ring tone maybe, and that would be used to trigger the blasting cap or whatever they've set up as the initial explosive.

Why do you think the bombs failed to explode?
The phone wasn't wired properly, or maybe the wiring came loose because something shifted. Even a dead battery could stop it—all sorts of things could go wrong. The British authorities will be able to figure that out.

How common is it to use cell phones as a trigger?
The technique has been around for at least five or six years. One of the bombings in Bali, Indonesia [in 2002], had a cell-phone device. And obviously they're used in Iraq.

What clues can investigators find in the bomb devices themselves?
You can see if [the bombers] were sloppy and didn't wear gloves and left fingerprints on the device. They can look at what materials and techniques were used in constructing it—not just the explosive material, but everything down to what screws were used—little details like that. That's called the bomber's signature. The explosive itself could be something as simple as the gunpowder they got out of a shotgun shell, or it could be something they mixed up themselves, like a peroxide-based explosive. These are materials you could get at a beauty store. That's why you can't take more than three ounces of any liquid on most planes now. They'll compare all that information with what they know about how different groups make bombs.

Can investigators tell how much damage the bombs could have caused by what they find?
Absolutely. Based on the amount of explosive and how it was arranged, they can estimate how much damage it might have caused. And they can go the other way and work backwards from a bomb site.

What kind of destruction can a car bomb cause?
We don't know exactly what was in these cars and how much of it was explosives, and the authorities won't release that information for security reasons. But as an example, you could look at any of the car bombs that go off in Baghdad. It depends on how many people are around at that time. The truck bomb in Bali killed several hundred people because it was detonated next to an outdoor party during a holiday season. In this case, the gasoline would make it into a fireball. And that could start other fires and do damage to surrounding buildings and structures.

What will they look for in the cars themselves?
First, the car would be gone over for fingerprints. That would be the most useful thing. Then they'd look for any other trace evidence that might be able to tie a suspect to the car. There's a forensic principle called the Locard principle. He was a French criminologist who said every contact leaves a trace. Simply put, if you went and sat in someone's car, and then got out, you've left fibers from your clothing and you've also picked up fibers from the car. That kind of thing has been used by forensic scientists for years to associate people with a crime scene or with the victim.

How would investigators use that kind of basic evidence in this kind of case?
Say, in a hypothetical situation, you've got a suspect, but you haven't convicted him yet. You have a cell phone you've tracked to this suspect. He could say someone stole my cell phone. But if you can find one of this suspect's hairs in the car involved in the bomb plot, and then if you use DNA technology to confirm that it's his hair versus anyone else's hair, you can associate him with the car. Now that means that you can say, if your phone is stolen, how did your hair end up in the vehicle? All of this is traditional forensics.

What about the surveillance cameras that were in the area at the time? How can investigators use those?
Well, they're probably going through their security-camera records so they can see who left those cars there. Great Britain has an extensive set of cameras throughout the country [CCTV cameras].

Can they use facial-recognition technology on the surveillance footage?
Some of that technology works really well—some of it doesn't. We've seen cases where if the guy [being sought] combed his hair another way, it threw the machine off. It depends on the quality of the camera and the situation. One thing they can use it for is to scan the tapes to eliminate people who are not suspects. If your suspect is a man, you might go through and have it hone in on people of that approximate height and weight and eliminate females. That can be done automatically. But with this kind of matching, and any other kind of matching, like fingerprints, you can't say it's him definitively with that evidence alone. At least not in the United States. All we can say is that we have not been able to eliminate this person.

How long will it take to analyze the evidence they have?
They're going to get answers back on things like what kind of explosive were used in a few hours. If they've got to do DNA analysis it might be a few days. Obviously, this will be a priority.