Examination of bomb scene evidence is an area of increasing involvement for the forensic scientist in which incidents may vary from student mischief to mass murder, or both. In order to undertake explosive casework responsibilities, the investigators must have personal experience with the type of primary physical evidence left after explosions. These may include the remains of explosive devices, characteristic damage to the surrounding setting and structures, and chemical residues present on the surfaces of damaged goods.

Recognition of device remains is aided by law enforcement agency publications, such as the FBI Laboratory Division's Explosive Unit-Bomb Data Center (EU-BDC). The significance of damage in bomb incident investigation has been discussed in general terms (1) and explosive damage to metal has been studied (2).

Chemical residues may contain unreacted explosive components and also condensed reaction products.   Solid products have been studied less than gaseous products, but have been reviewed for black powder and chlorate / perchlorate mixtures. Smokeless powders yield nitrites which form the basis of propellant powder pattern tests. Since solid reaction products from dynamite do no work, their chemical composition has been deduced more from thermodynamic calculations than analysis (3). Published methods (4 - 31) for explosive residue analysis include optical microscopic and scanning electron microscope examination for unreacted explosive, as well as chemical spot tests, thin-layer chromatography (TLC), X-ray diffraction and IR spectroscopy (22-23) for products of the explosive chemical reaction.

Beveridge, et al. (24) conducted a systematic analysis of a wide variety of explosive residues isolated by physical removal or solvent extraction. Their techniques included a combination of IR spectroscopy, TLC, X-ray diffraction, emission spectrography, optical microscopy and chemical spot tests. X-ray powder diffraction permits non-destructive identification of crystalline minerals and materials by comparison of diffraction patterns to ASTM standards. An emission spectrograph is useful for identification of explosive metallic content such alkali metals (Na, K, etc.) and manufacturer additives. Spot tests were used to check ionic species such as the nitrate ion (NO2-) which in low yield (< 10 %) might be missed by instrumental analysis, and for rapid screening of high yield residue. Applications to residue analysis were demonstrated by test explosions using black powder, smokeless powder, chlorate / sugar, dynamite, C4 plastic explosive, and PETN-based detonating cord. A glossary of terms is included below, as well as a list of explosive components identified as well as their sources.

I. Low Explosives

Low explosives confined in steel pipes with threaded end caps exploded on flame initiation. Black powder gave pipe fragments with fresh rusty areas and a  high yield of grayish residue. Unreacted granules were commonly recovered in pipe threads and sometimes in the body of the pipe. The surroundings were usually blackened. Debris from the explosion included thiocyanate which was identified by IR spectroscopy in an acetone extract.

Black powder residue consisted primarily of potassium sulfate identified by X-ray powder diffraction. An IR spectrum of typical residue showed strong sulfate and weak nitrate absorption. Weak carbonate peaks were also observed in some trials. The safety fuse also gave potassium sulfate as principal residue from the black powder core. Recognition of unreacted black powder granules by optical microscopy was essential, or the identification of explosive would have to have been based solely on reaction products. 

Single-base smokeless powder consisted of NC cylinders coated with graphite and DNT to control burning. it also contained a small amount of potassium sulfate additive. In a cap-initiated pipe bomb in the corner of a room, no wall push was observed, unreacted explosive was thrown around the room, and a devastating fire was started within the wall.

Double-base smokeless powder consisted of graphite-coated NG and NC, plus a small amount of Potassium sulfate additive. A flame-initiated 0.5 lb. charge in a closed room blew out the windows and showed some wall push (deformation of wall structure), but left a light bulb intact in the ceiling. Out of twelve fragments recovered from the walls and crater, five contained unreacted explosive. All fragments showed fresh rusty areas and traces of resinous residue. NG and NC were identified by IR and TLC. Aqueous extraction gave a low yield of contaminants in which sulfate was identified by IR and sodium by spectrography. Spot tests showed nitrate, nitrite, ammonium, and chloride. The X-ray powder pattern was not identified as a known crystallographic structure (as opposed to those clearly identified in dynamite trials).  

Chlorate / sugar produced a fireball and explosion on flame initiation. Unreacted explosive was recovered. Pipe fragments bore brown gummy residue and fresh rust spots. Extraction yielded unreacted sugar and sodium chlorate identified buy IR, and the sodium chloride product identified by optical microscopy and X-ray powder diffraction.

II. High Explosives

Dynamite is the class of explosives most often encountered in bombing incidents. The classes of dynamite used in this study were gelatin (NG, NC), ammonia (NG, NH4NO3), and ammonia gelatin (NG, NC, NH4NO3). Nitroglycerine dynamites typically contain up to 85 % ethylene glycol dinitrate (EGDN) with the nitroglycerine. The EGDN depresses the freezing point of the NG, which lessens the risk of dynamite becoming unstable through freezing and thawing. The EGDN is, however, more volatile than NG and is the basis of "dynamite sniffers". The dynamite in this study contained sodium nitrate and sulfur for oxygen balance, except for the gelatin which did not contain elemental sulfur. None of these dynamites contained the common additive DNT.

It has been predicted that dynamite with sodium nitrate should yield sodium carbonate. In the presence of sulfur, co-products may include sodium sulfide, sulfite, and sulfate, depending on the oxygen balance. For the ammonia gelatins, predicted products are primarily sodium sulfate and sodium carbonate. These predictions point to TLC and X-ray diffraction as prime identification techniques.

Ammonia Dynamite. In two different explosive trials (on wood and steel surfaces), a white crystalline residue was observed, which was not recognizable as unreacted dynamite. Acetone extraction and TLC identified NG in the exploded wood crater in one case, but not in the surroundings. Aqueous extraction yielded white crystals, and the IR spectra showed the presence of sulfate and carbonate products in addition to unreacted nitrate. X-ray powder diffraction of the mixture identified the product from the wood crater as Na2SO4 (a metastable form of sodium sulfate which is stabilized by carbonate ion), while the residue from the trial on steel was identified by IR as sodium carbonate sulfate. The different results are explained on the basis of the partial deterioration of one stick vs. the other. The product composition is apparently determined by the mole ratio of carbonate ion to sulfate ion.

Ammonia Gelatin Dynamite. The velocity of 40% Forcite is ~ 7000 feet per second unconfined and 13,000 fps confined. Velocities are proportionately higher for 60% and 75%. The variation of velocity with confinement is typical of gelatin dynamites. Tests in residential premises showed a marked contrast to the low explosives. Walls were shattered (as opposed to pushed) and the reverse blast brought window glass back into the rooms. When confined in pipes, some pipe fragments passed through several walls and doors. In very few trials was unreacted explosive recovered in the debris.

The confined explosives were distinguished form the unconfined explosives by the composition of the reaction product as determined by X-ray powder diffraction. The confined explosives gave sodium carbonate sulfate, whereas the unconfined gave Na2SO4. Unconfined Forcit residue showed no carbonate in the IR spectrum. The presence of some carbonate was inferred, however, form effervescence with acid. There was insufficient sodium nitrate in the confined explosive residue for identification in the X-ray power pattern. But it was recognizable in the bulk sodium carbonate sulfate matrix by optical microscope.

Sodium nitrate was identified by X-ray powder diffraction in all unconfined explosions, and NG was identified by TLC in ~ 75% of the explosions. However, ammonium nitrate and NC were detected in less than 50% of the tests. Where a TLC system was used which separates EGDN from NG, EGDN was found in only one-third of the cases in which NG was identified. This cautions against complete reliance on a "dynamite sniffer" to detect residue.  

Plastic C4. The velocity of C4 is ~ 25,000 fps. C4 was detonated by either blasting cap or detonating cord booster. No unreacted explosive observed in the characteristic black deposit. In only one out of three explosions was RDX identified by TLC. On one piece of debris, PETN form detonating cord booster was also identified.

Detonating Cord. The detonating cord was charged with PETN. In one of two explosions, PETN was identified by TLC. In both cases, traces of wrapper were recovered.

This analytical scheme was derived from practical experience and previous literature and uses the instruments used routinely in Royal Canadian Mounted Police (RCMP) laboratories (24). The results indicate that the scheme permitted correct classification of the explosives, although subclassification of dynamite was not always possible. Unreacted explosive in debris was recognized by microscopic examination for most of the low explosives, few of the dynamites, and none of the plastic explosives.  

In a separate study by the Bureau of Alcohol, Tobacco and Firearms (U.S. Dept. of Treasury, Washington, D.C.), both microscopic and chemical spot test techniques are utilized to evaluate explosive residues. Hoffman and Byall (25) emphasize that traces of unconsumed residues are invariably mixed with soil, concrete, or other debris. The residue traces are rarely, if ever, visible to the naked eye. So the collection of the residues depends upon taking samples of debris from those locations at the blast scene (e.g. explosive craters) most likely to contain them. In addition to the bomb's original location, other good sources of explosive residue are the objects located near the device on detonation. Wood, insulation, rubber, or other soft materials which are readily penetrated often collect traces of the explosive.

Microscopic examination has been described in detail by Washington and Midkiff, et al. (12 - 21). Hoffman and Byall point out that the microscopic examination of the debris can only be effective if the examiners has learned to recognize particles of undetonated explosive when they see them. Black powders and smokeless powders are relatively easy to detect in debris of most types because of their characteristic shapes and colors. Dynamite, which is an amorphous mixture, is found in a variety of colors and is much harder to find, especially in soil.

After particles of the suspected explosive have been recovered form the debris, their composition must be chemically confirmed in almost every case. The possible exception to this is smokeless powder which has a unique appearance. In the case of other explosive residues, the general appearance of the material will suggest the confirmational chemical test to be run.

Black powder is manufactured in a variety of granulations and can be either glazed or unglazed. Usually it is found in debris because it contrasts so markedly with its surroundings. Particles may be readily tested by observing their burning characteristics. Hold a particle suspended on the tip of a dissecting needle over a small flame. Black powder will instantly burn with a characteristic flash -- producing a trace of white smoke. (An alternate method is to extract the particle and test the resulting solution for the presence of nitrates or sulfur by procedures described below).

Smokeless powder is produced in a variety of unique shapes, and the powder can often be identified with respect to type and manufacturer if suitable reference standards are available. The most commonly encountered smokeless powders are bulk powders used by handloaders. The smokeless powder can be  burned if confirmation of its identity is needed.

RDX Compounds. C4, often referred to as plastic explosive (for its shape charge capabilities) is white in color and dough-like in consistency. Although it is the most commonly encountered of the RDX explosives, it is not frequently used in criminal bombings in this country if the cases examined by the ATF Forensic Lab are representative.

Chemical spot tests can be performed on a particle of the suspected C4. Place the particle on a white enamel spot plate with milligram quantities of thymol crystals. Intimately mix these substances with the tip of a glass stirring road and add 3 drops of sulfuric acid. The formation of a rose color upon addition of 5 drops of ethyl alcohol indicates the presence of RDX.

Thin-Layer Chromatography (TLC) procedures described by Jenkins and Yallup (8) can be used to verify that that the material is an RDX-based compound. If sufficient material is recovered from the debris, it can also be examined by IR spectroscopy in order to confirm its identity by comparison with known standards. These procedures are described by Pristera, et al. (22) who have compiled an impressive list of IR spectra for a variety of explosive compounds.

Trinitrotoluene (TNT). Like many other military explosives TNT is rarely used in bombings in this country. Particles of this material can be tentatively identified by their melting point (81 degrees C) and confirmed with a chemical spot test. Place the suspected TNT in a white spot plate and add 2 drops of ethyl alcohol which has been saturated with potassium hydroxide. A deep red color indicates the presence of TNT. IR analysis and TLC may also be carried out if a sufficient quantity of the suspected explosive is restored.

Dynamite is by far the most commonly encountered high explosive used in destructive devices associated with criminal acts in this country. There are a number of types of dynamite, including straight dynamite, ammonia dynamite, blasting gelatin, ammonia gelatin, and nitrostarch dynamite. These explosive compounds have wide variations in color, from off-white to nearly black.  

While there are a wide variety of dynamite formulations, there are only a few components which need to be identified in order to confirm the presence of dynamite residues in bomb debris. These components are sulfur, ammonium nitrate, sodium nitrate, and the explosive oils [nitroglycerine (NG) and thylene glycol dinitrate (EGDN)] absorbed on the binder or "dope" which makes up the bulk of the dynamite compound.

Not all of these components will be present in every type of dynamite and, hence, not in the debris from every dynamite bomb. Even dynamites of the same type have differences in their compositions. E.G. Straight dynamite up to 30% strength contains about 2% sulfur, while higher strength dynamites usually do not contain this component.

Most dynamites contain sodium nitrate, but only ammonia dynamite contains ammonium nitrate. In contrast, all commercial dynamites, with the exception of nitrostarch dynamite, will contain explosive oils in their binders. A comprehensive discussion of the specific compositions of the various types of dynamites can be extremely detailed and requires a more in-depth study of thorough coverage of this subject matter (28 - 31).

The identification of dynamite in bomb debris is based on the detection of the explosive oils (NG / EGDN) and one or more of the inorganic components. The identification of these individual components is discussed here, beginning with the inorganic nitrates.

Ammonium Nitrate and Sodium Nitrate. Usually these compounds are easily found in dry debris since they are normally present in the form of prills (spheres ~ 1 mm in diameter) which contrast markedly with their surroundings. The prill is tested by dissolving it in 2 or 3 drops of water and analyzing the resulting liquid for the presence of sodium, ammonium and nitrate ions.

Inorganic Nitrates in solution may be detected by the diphenylamine, nitron, or modified Greiss tests. Addition of 2 drops of diphenylamine reagent to the test solution will produce a deep blue color in the presence of nitrates. However, other oxidizing agents will also give the same color reaction. For this reason, diphenylamine is most useful as a simple screening procedure. Addition of nitron reagent to the test solution gives the highly insoluble nitron nitrate as a white precipitate. The Greiss test is performed by adding to the test solution 1 drop of sulfanilic acid solution, followed by the addition of 1 drop of alphanaphthylamine solution. Addition of zinc dust will reduce nitrate ions to nitrite ions, which in the acid solution will bring about diazotization and coupling to produce a deep red color. The latter tow tests are both specific for detecting the presence of inorganic nitrates.

Ammonium Ion is detected in the test liquid by the addition of Nessler reagent, and the presence of sodium (Na+) ions may be detected wither by a simple flame test or by atomic flame absorption.

Sulfur has a characteristic granular yellow appearance in dynamite residues resembling small pieces of cracked whole corn. A very sensitive test for elemental sulfur involves placing a fragment of the suspected sulfur (~ 1/4 the size of a pinhead) in a small test tube and adding 1 ml of pyridine. After gently warming the tube to dissolve the sulfur, add 2 drops of 2 N sodium hydroxide solution or a saturated solution of sodium bicarbonate. Depending upon the concentration of sulfur in the test solution, a blue to green color is produced.   

Nitroglycerine (NG) and Ethyleneglycol Dinitrate (EGDN). The detection of NG and EGDN on the particles of dope recovered from the debris is best accomplished by TLC. The particles to be tested are treated with a few drops of acetone in order to extract the explosive oils form the dope. The volume of the extract is reduced by air evaporation, the concentrated liquid is spotted on a TLC plate, and the plate is developed in a 4:1 carbon tetrachloride/dichloroethane mixture. (As with any TLC analysis, standards are run on the same plate for comparison. 

The plate is removed from the tank and dried after the solvent front has moved 10 cm. The plate is lightly sprayed with a diphenylamine/sulfuric acid solution. NG and EGDN appear as well-defined and distinct spots with R(F) values of 0.4 and 0.6, respectively. If additional material from the debris is available, the TLC examination should be repeated using another solvent system such as 1:1 benzene/hexane, and an IR spectrum should be obtained.

Ammonium nitrate prills mixed with 4 - 8 % fuel oil is commonly known as ANFO. ANFO is rarely used in bombs because of the ready availability of more easily initiated explosives. In order to be effective, this material must be packaged in a sturdy container and initiated with a high explosive booster. The resulting bulk is usually undesirable form the bomber's point of view. The presence of ammonium nitrate can be chemically confirmed by the tests described above. The fuel oil component can be extracted with an organic solvent such as carbon tetrachloride and identified by gas-liquid chromatography.  

Improvised Low Order Explosive Mixtures made from commonly available chemicals fall generally into two categories: homemade black powder and homemade flash powders. These mixtures are usually confined in some container such as a section of capped pipe, and initiated with an external burning pyrotechnic or homemade fuse.

Homemade Black Powder is a mixture of potassium nitrate, sulfur, and charcoal. It is often poorly assembled, and unconsumed (or unreacted) particles are typically abundant in the bomb debris. The components in this mixture can be chemically identified using techniques described previously.

Homemade Flash Powder mixtures have a variety of chemical formulations. They usually contain finely divided aluminum or magnesium metal and an oxidizing agent such as ammonium nitrate, potassium chlorate, or potassium perchlorate with possible additions of sulfur and/or sawdust. Some of the components of flash powders can be identified by tests described above or by their microscopic appearance. Magnesium may be identified by its burning characteristics and its solubility in nitric acid (HNO3). Aluminum metal will dissolve in dilute sodium hydroxide (NaOH) solution with the liberation of hydrogen (H2) gas and is insoluble in nitric acid.

Chlorates. The presence of chlorates may be verified with the aniline sulfate test. To a few drops of an aqueous extract of the flash powder, add 2 drops of a 1% aniline sulfate solution. Allow 5 drops of concentrated sulfuric acid (H2SO4) to slowly run down the side of the test tube so that two layers are formed. After ~ 1 minute, the formation of a blue-violet color at the interface of the two liquids is indicative of the presence of chlorates.

In addition to IR spectroscopic analysis, the index of refraction can has been found to be quite useful in the characterization and identification of inorganic salts from flash powders or other explosive mixtures. Specific values of the refractive index n include:

Index of Refraction

Ammonium Nitrate :  1.611

Sodium Nitrate:  1.587

Potassium Chlorate: 1.517

Potassium Nitrate: 1.504

Potassium Perchlorate: 1.474   

A separate group from the Bureau of Alcohol, Tobacco and Firearms (U.S. Dept. of Treasury, Cincinnati, OH) performed a thorough analysis of explosives and explosive residues using chemical spot tests and thin-layer chromatography (TLC). Parker, et al. (27) conclude that TLC is a good confirmatory test for nitroglycerine, PETN, RDX, and TNT. The results are shown here using chloroform as a solvent.

In addition, a quick screening process may be successfully accomplished using chemical spot tests for these compounds. E.G. If no positive Greiss test is obtained, then no nitriles, nitrates, or nitro-containing organic compounds are present, with the possible exception of nitrotoluenes (TNT or DNT). For other anions, IR spectroscopy is recommended for absolute confirmation of chemical composition and identity, as clealry evidenced by the work of Pristera, et al. (22).

It is also noted by these workers that caution should be used in the interpretation of the significance of positive tests for ammonium nitrate, since this is the primary constituent of fertilizer. it will quite often be found in soil samples and other evidence which has come into contact with dirt (e.g. shoes, car floor mats and door mats, etc.). In this particular study, the presence of ammonium nitrate in a sample, unless accompanied by evidence of other explosive compounds (or if it would not ordinarily be present in that particular type of sample) is treated as inconclusive evidence of the presence of explosives. The tests found to be most useful in this study are:

1) The Greiss tests for nitrate ions

2) The Nessler test for ammonium ions

3) The Silver Nitrate test for chloride ions

4) The Barium Chloride test for sulfate ions

5) The Sulfur test

6) The Potassium test papers

7) The Zinc Uranyl Acetate test for sodium ions. 

~~~~~~~~~~~~~~~~~~~~~~~~

References / Reading

~~~~~~~~~~~~~~~~~~~~~~~~

1)  Yallop, H.J.

J. For. Sci. Soc., Vol. 5, p.6 (1965)

2)  Tardiff, H.P. and Sterling. T.S.

J. For. Sci., Vol. 12, p.247  (1967)

3)  Cook, M.A.

Science of High Explosives

Rheinholdt, New York (1958)

4)  Amas, S.A. and Yallop, H.J.

J. For. Sci. Soc., Vol. 6, p.185 (1966)

5)  Urbanski, T.

Chemistry and Technology of Explosives

Permagon Press, New York (1967)

6)  Lloyd, J.B.F.

J. For. Sci. Soc., Vol. 7, p.198 (1967)

7)  Amas, S.A. and Yallop, H.J.

Analyst., Vol. 94, p. 828 (1969)

8)  Jenkins,R. and Yallop, H.J.

Explosivstoffe, No.6, p.139 (1970)

9) Kempe, A.R. and Tannert, W.K.

J. For. Sci., Vol. 17, p.323 (1972)

10)  Maiti, P.C.

J. For. Sci. Soc., Vol. 13, p.197 (1973)

11)  Sanger, D.G.

J. For. Sci. Soc., Vol. 13, p. 177 (1973)

12)  Washington, W.D. and Midkiff, C.R.

"Systematic Approach to the Detection of Explosive Residues I. Basic Techniques"

J. Assoc. Official  Anal. Chemists, Vol. 55, p. 811 (1972)

13)  Washington, W.D. and Midkiff, C.R.

"Systematic Approach to the Detection of Explosive Residues II. Trace Vapor Analysis"

J. Assoc. Official  Anal. Chemists, Vol. 56, p. 1239 (1973)

14)  Midkiff, C.R. and Washington, W.C.

"Systematic Approach to the Detection of Explosive Residues IV. Military Explosives"

J. Assoc. Official  Anal. Chemists, Vol. 60, p. 331 (1976)

15)  Washington, W.D. and Midkiff, C.R.

"Systematic Approach to the Detection of Explosive Residues V. Black Powders"

J. Assoc. Offical  Anal. Chemists, Vol. 60, p. 1331 (1977)

16)  Washington. W.D. and Midkiff, C.R.

"Forensic Applications of Diamond Cell-IR Spectroscopy

I. Identification of Blasting Cap Leg Wire Manufacturers"

J. For. Spec., Vol. 21, p.862 (1976)

17)  Washington, W.D., Midkiff, C.R. and Snow, K.B.

"Dynamite Contamination of Blasting Cap Legwire Identification"

J. Assoc. Official Anal. Chemists, Vol. 60, p. 1331 (1977)

18)  Kopec, R.J., Washington. W.D. and Midkiff, C.R.

"Forensic Applications of Sapphire Cell IR Spectroscopy:

Companion to the Diamond Cell in Explosive and Leg Wire Identification"

J. For. Sci., Vol. 32, p. 57 (1978)

19)  Peimer, R.E., Washington. W.D. and Snow, K.B.

"On the Examination of the Military Explosive: C-4"

J. For. Sci., Vol. 25  (1980)

20)  Midkiff, C.R.

"Arson and Explosive Investigation"

For. Sci. Handbook, Vol. 1, p.222 (1982)

21)  Kinard, W.D. and Midkiff, C.R.

"Developments in Firearms Residue Detection"

Forensic Science (2nd Edn.)

American Chemical Society, Washington, D.C., p. 241 (1986)

22)  Pristera, J,. et al.

"Analysis of Explosives Using Infrared Spectroscopy"

Analytical Chemistry, Vol. 32, p.495 (1960)

23)  Chason, D.E. and Norwitz, G.

Microchemical Journal, Vol. 17, p. 32 (1971)

24)  Beveridge, A.D., et al.

"Systematic Analysis of Explosive Residues"

J. For. Sci., Vol. 20, p.431 (1975)

25)  Hoffman, C.M. and Byall, E.B.

"Identification of Explosive Residues in Bomb Scene Investigations"

J. For. Sci., Vol. 19, p.54 (1974)

26)  Parker, R.G., et al.

"Analysis of Explosives and Explosive Residues I: Chemical Tests"

J. For. Sci., Vol. 20, p.133 (1975)

27) Parker, R.G., et al.

"Analysis of Explosives and Explosive Residues II: Thin-Layer Chromatography"

J. For. Sci., Vol. 20, p.133 (1975)

28)  Yinon, J. and Zitrin, S.

Analysis of Explosives

Permagon Press (1982)

29)  Cooper, P.W. and Kurowski, S.R.

Introduction to the Technology of Explosives

John Wiley & Sons - VCH (1996)

30)  Yinon, J. and Zitrin, S.

Modern Methods and Applications in Analysis of Explosives

John Wiley & Sons, New York (2001)

31)  Meyer, R,. Kohler, J. and Homburg, A.

Explosives

John Wiley & Sons, New York (2002)

32)  Akhavan, J.

The Chemistry of Explosives (2nd Edn.)

Royal Society of Chemistry, Cambridge, UK (2004)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

12 June 2003

FBI Says Cellular Phones Rigged To Set Off Bombs

WASHINGTON, DC: The Federal Bureau of Investigation said on Wednesday that while it was looking into the recent terrorist bombing in Saudi Arabia it found cell phones rigged to detonate explosives by remote control. The Bureau urged U.S. law enforcement officials to be on the lookout for similar devices. According to a weekly FBI bulletin to 18,000 state and local law enforcement agencies, the modified cell phones turned up during searches following the 12 May bombing in Riyadh that killed 35 people, including nine Americans. ERRI analysts say this is not a new tactic. It has been used extensively in the Middle East, particularly as designed by Palestinian militants like "The Engineer," Yahya Ayyash. Ayyash was reportedly killed by a remote-detonated cell phone several years ago.

Although the FBI said it has no information indicating any of the tens of millions of existing cell phones would be used by terrorists in the United States, the bulletin urged local officials to take precautions if a suspected device is found. The bulletin said that if officer encounter such a device, they should "immediately evacuate the area to a minimum distance of 300 yards. Radios, cellular telephones and pagers should not be used within 50 feet of the suspected device." The FBI said that terrorists also have used pagers and radio systems to detonate bombs by remote control.

The FBI bulletin included details of how a cell phone can become part of a deadly bomb. It requires use of a battery, a switch, an initiation device such as an electric match or a light bulb, conducting wires and explosives. The phone itself is not a bomb. When the phone receives an incoming call, "the electrical power from the telephone's ringer or vibrator activates the bomb's circuitry" causing an explosion. The bulletin warned that "law enforcement officers without specialized explosives training should never attempt to remove or disable a suspected device." ERRI analysts said that the FBI warning goes double for Fire/EMS or other first responders who don't have an extensive knowledge of explosive ordinance disposal techniques.

ERRI senior national security analyst Clark Staten said today that more needs to be done to train all emergency responders in regard to the identification of Improvised Explosive Devices (IEDs), that they may increasingly encounter in the United States.
 

~~~~~~~~~~~~~~~~

17 May 2003

U.S. Public Warned To Be On Alert For Truck Bombers

WASHINGTON: The U.S. State Department issued a nationwide alert on Friday for the U.S. public and American businesses to be on the look- out for possible attacks by suicide truck bombers in this country. Saying it had no specific information that a truck bombing of any kind was being planned in the United States, the DoS -- through its Overseas Security Advisory Council (OSAC) -- said the nationwide alert was designed to pre-empt any such attack by advising the public as well as people who own and operate businesses on how such a terrorist event might take place. The alert, noting that the Department of Homeland Security believes a truck bombing by terrorists may be pre-empted if the general public remains on guard for certain indicators, outlined what it called general information to assist in recognizing potential truck bombers or other threats based on the Monday bombings in Riyadh, Saudi Arabia.

Asking the public to watch for and report any suspicious activity, the alert listed several indicators or actions that could be a precursor to an attack, including:

-- Chemical fires, toxic odors, brightly colored stains or rusted metal fixtures in apartments, hotels, motels or self-storage units.

-- The rental of self-storage space for the purpose of storing chemicals or mixing apparatus.

-- The delivery of chemicals directly from the manufacturer to a self- storage facility or unusual deliveries of chemicals to residential or rural addresses.

-- The theft of explosives, blasting caps, fuses or certain chemicals used in the manufacture of explosives.

-- Small test explosions in rural wooded areas or the treatment of chemical burns or missing hands or fingers.

-- The modification of a truck or van with heavy-duty springs to handle heavier loads.

The alert noted that international terrorist groups have demonstrated the ability to plan and conduct complex attacks simultaneously against multiple targets. In the Riyadh attacks, it said, terrorists -- suspected of being linked to the al-Qaeda network -- assaulted three compounds occupied by Western guest workers using multiple vehicles. At least one vehicle in each assault team carried a large explosive charge, which was detonated by a suicide bomber.

The alert said media reports indicated that the attackers drove up to each compound, killing those guarding the compound gates with small-arms fire. Vehicles carrying the explosive charges were then driven into each compound and detonated. In one instance, the alert said, it appeared the terrorists attempted to breach the gate security checkpoint by ramming it with a sedan.

It is likely that those involved with executing the Riyadh attacks conducted extensive preoperational surveillance of the compounds selected, the alert noted, adding that meticulous planning to include surveillance is a hallmark of al-Qaeda terrorist attacks. While the ability to conduct multiple, near-simultaneous attacks against several targets is not new for terrorist groups such as the al-Qaeda network, the alert said the manner in which the Riyadh attacks were conducted indicated a more refined capability. The alert said that the split-second timing among the three attacks showed that a trained and dedicated cadre perpetrated the assault.

The Department of Homeland Security sent the bulletin warning the operators and owners of various facilities in the United States to be vigilant. The DHS sent the seven-page bulletin to business organizations, state and local governments, and state and local law enforcement agencies. 

Source:  Risk Assessment Division, Information Analysis Directorate, Department of Homeland Security.