Michael Marks

These were two relatively sophisticated devices that went off almost simultaneously. They had a very, very short delay, it would be my opinion that they had somebody who was more of a skilled bomb maker, an engineer if you will, assist them in saying these are the steps you need to go through and then assemble the device to make it safely and to make it function the way they want.

You want a separate circuit tester in order to test the functionality of the components without it being hooked up to the actual device, for your own safety.