FORENSICS 165: OUTDOING THE DOGS
This essay might be of special interest to writers of detective and mystery novels who would like to enrich their stories by providing their readers with a gift of extra details. It might also be of general interest to many other readers, especially those who are CSI and NCIS fans.
Smithereen is a powerful word. If one reads that something has been broken, it usually conjures an image of something that can be fixed and made useful again. If one reads that something has been smashed to smithereens, however, it conjures an image of tiny fragments of what is now utterly useless. There are persons, though, who often find smithereens extremely useful. These special persons are forensic examiners. The following describes a case in point.
Within the first 38 minutes after takeoff from Heathrow Airport in London, a Boeing 747 had reached an altitude of some 31,000 feet. Clearance to begin an oceanic segment of a flight to NY had been issued. A blip representing the plane on a tracking radar screen confirmed that it was right where it should have been. All seemed to be proceeding smoothly when the single blip suddenly disintegrated into a number of blips, the movements of all indicating a new, downward course. A bomb had exploded inside a baggage compartment of the plane. It was four days before Christmas in 1988.
What must have been an unimaginable, horrific scene within the plane was shared with observers on the ground, who watched as body parts as well as aircraft parts and flaming fuel showered downwardly. Wreckage was spread over an area of 50 square miles, and debris, over an area of 845 square miles. A wing of the plane struck the ground with such force that it plowed a crater 155 feet long, displacing some 1500 tons of dirt as it did so. All 259 persons aboard the plane were killed, as were 11 persons on the ground, and 21 houses were completely demolished. Thus ended the flight of Pan Am 103 over Lockerbie, Scotland.
The explosion initiated an intensive investigation whose research extended into more than 40 countries. Some 180,000 pieces of evidence were examined, and 15,000 persons were interviewed. It was determined that the bomb was made of Semtex, a malleable, general-purpose, plastic explosive used by civilians and military personnel. It was favored by terrorists because it was extremely difficult to detect (which is no longer the case). The explosive was secreted within a Toshiba radio-cassette player packed in a brown, Samsonite suitcase.
Fortunately, in a forest 80 miles from Lockerbie, a man walking his dog discovered a T-shirt having pieces of a timer suspected to have been used in the Lockerbie bomb. Examination of the T-shirt and timer pieces ultimately provided the names of two men suspected of being responsible for the explosion on the Pan Am flight. It took eleven years before the two suspects could be brought to trial in the Netherlands. In 1999, one of the two suspects was sentenced to life in prison, and the other was acquitted.
The lives of the 259 persons on the plane and the 11 on the ground need not have been lost had a device capable of detecting the explosive that brought the Pan Am plane down been used to screen items and persons being loaded aboard it. Due to terrorist activities, interest in developing such a device has been keen. A promising device has been developed that reportedly equals or betters the performance of highly trained sniffer dogs, which have long deserved a commanding reputation in the various fields of sniffing. Fittingly, the device is referred to as Fido.
It can be handheld or mounted on an apparatus such as a tracked military robot that can take it where humans dare not go. Fido can detect both explosive vapors and particulates. It’s sensitivity is such that it detects explosive materials in parts per quadrillion (ppq). Fido can detect vapors from buried land mines and has even, without the aid of preconcentration, detected a plume of explosives in sea water. Fido has seen duty in explosive ordnance disposal (OED) applications in such foreign hotspots as Iraq and Afghanistan, and it has been used in the U.S. for explosive detection operations. It’s usefulness has been recognized by having won the U.S. Army Greatest Invention Award multiple times.
A major key to the Fido operation includes amplifying fluorescent polymers (AFP). Electrostatic and oxidation-reduction properties of AFP, contribute to a high level of selectivity, minimizing false alarms.
The inside surface of of a glass capillary tube is coated with AFP to form therewith a sensing element. The presence of explosive vapors in surrounding air can be detected by inserting the sensing element into the detector and exposing it to a light source having a specific wavelength . The light stimulates the AFP, causing it to fluoresce. While the AFP is fluorescing, surrounding air is pulled through the sensing element. Traces of explosive vapor will react with the AFP, causing the fluorescence to dim, or “quench.” The structure of a chromophore chain in the AFP amplifies the quenching effect, which provides ultra-low detection limits. A quench is detected and maximized by optical and electronic components, which also maximize the sensitivity of the detector and notifies a user of the detector of the quench. Within a few seconds, the sampling response can be reversed to prepare the detector for additional samplings.
In addition to buried mines, bombs and such, a person’s skin, their clothing, tools, residences and means of transportation can also be sources of explosive vapors. Explosive detectors can be used to scan the sources to expose evidence that a suspect had been in contact with and possibly assembled or transported an explosive device.
As a parting thought, consider that, buried around the world, there are estimated to be millions of buried landmines and millions of acres of land containing live ordnance left from past battles. It makes one want to search catalogs for a pair of explosive-detecting shoes.
AFP was invented by MIT Professor Timothy M. Swager.
In a short-scale country like the United States, a quadrillion is equal to 1,000,000,000,000,000 (one thousand million million or ten to the fifteenth power).
A chromophore is a portion of a molecule that provides color.
A glass capillary tube is a tube having an inner diameter of a proper size to draw in a liquid as a result of capillary action.
Fluorescence is the emission of light by a substance in response to having absorbed electromagnetic radiation such as visible light.
A number of persons have taken advantage of the fear generated by widespread bombings to market fake explosive detectors. One person took advantage of countries having no technology capable of testing his phony device and made millions of dollars. Tens of millions were from Iraq, which equipped hundreds of check points with them. The worst result was the loss of lives caused by trusting the devices to discover explosives. Unbelievably, Iraq was still using the devices several years after they had been found to be fake and its seller had been sentenced to serve 10 years in prison.