Chemistry and the FBI Thomas 0. Munson a n d Linda C. Davidson Forensic Science Research Group Laboratory Division. FBI Academy Quantico. VA 22135
T h e m e n a n d women of t h e Federal Bureau of Investigation, Laboratory Division, located i n Washington, DC, perform virtually all of t h e forensic analysis of evidence reauired h v t h e FBI. T h e analvses involvine chemical methods tade place primarily ill t h e Scirnrit'ic Analvies S r r t i o n of t h e Flll Lnhoratorv. T h e FHI L a l x m t o r \ . e m o l o- v ~a .. rwnumately 400 people, a b o u t 100 of whom rouiinely perform chemical analyses. Since we cannot, i n t h i s one article, detail all of t h e t y p e s of chemical analyses routinely used at t h e FBI Laboratory, crime-scene scenario h a s been . a fictional . chosen a* a device to illuitrate specifically w m e of t h e m e t h ods a n d t o p r w i d e at least t h e flavor of chemistry a t work in modern criminal investigation. While t h e descriptions of t h e analytical techniques used a n d t h e d a t a generated a r e factua l t h e characters a n d events d e o i c t e d a r e fictional. T h e c o ~ r ~ t n u n i c a t i oproccdurei n between field a n d headquurtws A w n t s . 3s dtwicred in this article, a r e not factual but were ccanged s o t h a t t h e reader would n o t be encumbered b y detailed protocol.
-
E x c e r p t s from memos to t h e file g e n e r a t e d by S p e c i a l Agent (SAJ Michael Alexander Goodguy, - . FBI Field Office, .. City, USA. Monday, May 23, 1983: Responded to a police request for FBI assistance at Apartment 2C, 2819 West Strange Street. Two policemen had responded to a report of loud noises in the apartmentpossibly gunshots.They found asmall man (about 5ft. loin., 140lh) in his thirties, dead from a gunshot wound to the head. He had a gun in his hand. About 30minuteslater, alarge woman (Molly J. Brown, about 5 ft. 10 in., 155 lb) arrived. She said she lived with the man, whom she identified as Dale G. Macumber. She had bruises on her face and a gash with stitches in it on her forehead. The police department asked for FBI assistance because of certain items in Molly Brown's statement. She had advised the police that she lived with Dale Gordon Macumber for about four months but added that she didn't know very much about him. They met at the Starlite Lounge on East Strange Street on New Year's Eve. Ms. Brown said that on the night of Macumher's death, she and Macumber had gotten intoxicated and had begun to fight. He told her that if she didn't "shape up" he would kill her. Her response was to laugh at him and tell him that she didn't think he had the "guts" to kill anybody. At this point, he told her that he was involved with a terrorist organization and had done the three recent airport bombings that killed 33 people. Again, she laughed at him causing him to becomevery angry. According to Ms. Brown. Macumher said that he got started making bombs while helping a friend from college. He continued even after the friend was killed. He told Ms. Brown that he didn't know for whom he was working because they sent him coded instructions through the mail. He said they paid him with packages of $20 hills. Ms. Brawn said that he then showed her ashoe box full of $20 bills. Ms. Brown related that at this paint she began to belleve his story and became afraid. She said that she decided then to turn him in to the police while he was sleeping. Ms. Brown advised that Macumber caught her telephoning the police, threatened again to kill her, and ran into the bedroom to get his gun. Ms. Brown said she ran out of the apartment and drove off in her ear. She looked hack to see if Macumber was following her; this caused her to swerve the car and hit a light pole. According to Ms. Brown, this accident resulted in a facial iniurv which she had treated at a nrsrhy hvip~tal.When sht rcturne~t*~'hrruyartmcnr.shrinut~d the , killed h ~ m a d fm r l w p d l r r with hlacumher who. $he d t c ~ d e dhnd than he a r r ~ s r r dfur the Iwmbiny~and murder < f user XU peuple. If, indeed, Macumber was involved with a terrorist organization, this would be a matter requiring FBI assistance. ~
1054
~~
Journal
of Chemical Education
Minutes Figure 1. Explosives residue analysis. A few microliters of the solvent wash (methyiene chloride)of the plastic liner in a gym bag were analyzed for nitrogroup-based explosives residues using a high performance liquid chromatography (HPLC)system equipped with a thermal energy analyzer (TEA)detector. The HPLC separated the mixture of explosives residues into the individual explosive components ethylene glycol dinitrate (EGDN),nitroglycerin (NO), and pentaetyihritoi tetranitrate (PETN) which were then measured by the TEA detector. The TEA detector pymiyzes organic compounds convening the niw groups present to nitrosyl radicals which are oronated to excited-state nitrogen dioxide. Asthe excited-state nitrogen dioxide falls toground state, photons at light energy emined at 600 nm are measured by a phatomuitiplier tube. me TEA detector can detect as litlie as 15 Q 01 nitro group explosives.
Thursday, May 26,1983: SA Goodguy telephonically contacted SA Ted Grant (FBI Headquarters (HQ)), International Terrorism Section) about Ms. Brawn's story. SA Grant said the stacks af $20 bills and the coded messages matched an earlier investigation and he was most interested. SA Grant agreed that Macumber most likely would not have killed himself if he were a terrorist bomber. Several other inconsistencies were noted by SA Goodguy: the handgun had an obliterated serial number and had blood and hair on a portion of the handle which was shielded by the man's hand; Macumber's Tshirt had bloodstains on the front which didn't seem to have come from his wound; and his T-shirt had some smudges which looked like lipstick and makeup. SA Grant said it was critical to determine as quickly as possible whether Macumber was killed in a domestic quarrel with Molly Brown or whether he was executed by his employers. If his employers didn't know he was dead, it might be possible to trace hisnext message backup thechain to therest of the terrorist organization.
This is publication number 85-16 of the Laboratory Division of the Federal Bureau of lnvestiaation. Names of commercial manufacturers " are provided for identification only and inclusion does not imply endorsement by the Federal Bureau of Investigation.
Figure 2.Number restoration. In many cases where serial numbers have been removed from metal objects (such as automobile engines and firearms), the numbers can be made visible again with techniques combining metallurgy and electrochemistry. The photograph on the leh shows a portion of a US. Army rifle with the serial number ground off. The photograph on the right shows the same area of the same rifle which had been processed to restore the serial number.
Thursday, May 26, 1983: SA Goodguy delivered a crate to the Rapida Express Office on 29th Street for guaranteed overnight delivery to the FBI Laboratory in Washington, D.C. The crate contained the following items of evidence from the Macumher case: the handgun, Macumber's T-shirt, hand swabs from both hands of Macumher and Brawn for gunshot residue tests, the bullet recovered from Macumber's skull, hair and hlood samples from both Macumber and Brown, all of Brawn's cosmetics, and all af Macumber's luggage. Monday, May 30,1983: Supervisor Grant advised that aleadon the terrorist group had been developed. The Instrumental Analysis Unit found a profile of explosive residues in Macumber's plastic gym hag that matched the residues recovered from the debris of an airport bombing. SA Grant requested that the laboratory move the analysis of the rest of the evidence to top priority. [Authors' Note: When no visible bits of explosive material were found in any of the luggage, the luggage linkrs were swabbed with solvent and the solvent analyzed by highperformance liquid chromatography (HPLC). T o look far nitrogroup-based explosives, the HPLC was equipped witha thermal energy analyzer, allowing as little as 10 pg (10-l2 g) of such explosives to be detected. The mixture of the explosives (nitroglycerin, EDGN, and PETN) found on the lining of the plastic gym bag is shown in Figure 11. Tuesday, May 31,1983: SA Grant called with information concerning the examination of the handgun in the FirearmsfCoolmarks Unit. The bullet recovered from Macumber's skull was found to be toodamaged to compare it with one from that specific handgun. The caliber of the bullet and the class characteristics of the rifling marks on the bullet were found to he consistent with its having been fired fram the mdke and model handgun found a t the crime scene. Also, the Latent Fingerprint Section found no usable fingerprints on the weapon, hut that was not uncommon since most of the gripping surfaces on handguns are roughened and don't retain fingerprints. The Metallurgy Unit, using a technique combining metallurgy and electrochemistry, was able to restore the obliterated serial number on the handgun. [Authors'Note: Beforeandafter illustrationsof number restoration are presented in Figure 2. Specific details concerning the methodology for number restoration are confidential.] Grant searched the serial number through the FBI National Crime Information Center computer and found that the handgun was linked to a hank robbery case investigated by our field office. Wednesday, J u n e 1,1983: Anexamination of the Bank robbery file yielded some useful information, The robbery had been committed by three persons wearing ski masks-two large men and a large waman. Although the men were both too large to have been Macumber, the physical description of the waman was just about right to have been Molly Brown. The handgun was taken from a hank
Figure 3. Exploding money packet. Many banks are equipped with exploding maney packets which can be included with the money taken during arobbery. medve oroduced freouentlv ~,~ . . stains the robber's clothing (andlor sk1n)as well as themone,. often8 o ng n recovery of in? money an0 capt.rc of theroboer. Tne photograph on lne top shows m e aye c oud emanal ng from an exploaing dye paclef. an0 the pnotograpn a! the oonam s n o ~ rdye-stained money re~oversdfrom a bank robbery ~
-
guard by the masked woman. The bank was equipped with exploding maney packets which, when activated during a robbery, explode releasing a cloud of red dye. During the getaway, witnesses saw the hag the woman was carrying start to spout red smoke. The woman tried stamping on the hag to stop the smoke production. Failing in that attempt, she abandoned the hag and escaped. Because the' packets release a tremendous cloud of dye which stains whatever it touches, it's possible that she may have gotten some dye on her shoes. ------- IAuthor,~' , ~ - ~Note: Firmre 3 shows examples of the dye cloud produced by an exploding money packet add dye-stained money from a bag in which such a packet exploded.] All of Molly Brown's shoes fram the apartment were gathered up and taken over to Rapido Express for overnight delivery to the FBI Laboratory. Thursday, J u n e 2,1983: The Chief of the Serology Unit reported that all of the bloodstains were type 0 in the ABO hlood group system. Both Brown and Maeumber were type 0. Using gel electrophoresis to look at the haptoglobin profiles, however, they were able to show that the hlood on the front of Macumher's T-shirt and on the handle of the gun was not Macumber's, but may have been Brown's. [Authors' Note: Using tiny amounts of blood, such as single bloodstained fibers from a T-shirt, genetic variations in a particular protein can sometimes be used to discriminate bloods of the same ABO type. The use of polyacrylamide gel electrophoresis to separate the polymorphic forms of the glycopratein haptoglobin for comparison of several hlood samples is shown in Figure 4.1 The Microscopic Analysis Unit established by microscopic camparisons that the hair on the handgun had the same characteristics as head hairs taken from Molly Brown. The comparisons further estahlished that this hair was not a t all like head hairs from Macumber. The hand swabs taken by the police during their crime scene search were examined for their concentrations of antimony and barium by the Elemental Analysis Unit. These elements are eomponents of priming mixtures in many kinds of ammunition and can he deposited on the back of the thumb, forefinger, and connecting web areaof the hand when a firearm is discharged. The concentrations of antimony and barium measured on the swabs from Brown's and ~
Volume 62
Number 12 December 1985
1055
Macumber's hands were in the range of those found an the hands of persons who have discharged a firearm. [Authors' Note: When a firearm is dischareed - (Fie. 5 ) . a cloud of eunshot residues (GSR) . . is formed which contains. amone other comoonents. hieh coneentrahands and then analyzed by neutron activation analysis. The eoncentrations of antimony and barium on these swabs are compared to the concentrations found in a population of "nonshooters" and a population of "shooters."]
In addition, the Elemental Analysis Unit analyzed by neutron activation the lead bullet from Macumber's skull and the hullet from each of the cartridges left in the firearm far their alloying constituent, antimony, and trace impurities. They determined that all the bullets matched in composition and that the bullet from Macumber's skull and the other bullets probably originated from the same source of lead. A partially burned flake of gunpowder found attached to the hack of the lethal hullet was sent to the Chemistry/Toxicology Unit for comparison by gas chromatographylmass spectrometry (GCIMS) with the burnedgunpowder residue in the fired cartridgecase left in the handgun. The results of the comparison were consistentwith the assumption that the gunpowder flake attached to the lethal bullet was the same kind of gunpowder as had been in the fired cartridge case remaining in the handgun. [Authors' Note: Gas chromatographylmass spectrometry (GCIMS) couples the tremendous separating power of the gas chromatograph with the analytical capability of the mass s~eetrometer.A c o m ~ l e xmixture of oreanic ..~ comonunda rsuch a i th;,ir extracted irom dgunpuwder flake) mn be separated info individual wmpmnds: those c u m p w n d r n r e rhrn ionirrd, fragmented, and the mas- trngmrntdtiun pattern measurrd. 'hpn,file of compounds separated from a gunpowder flake and the pattern of the mass fragments as combined and displayed hy the computer datasystem areshown in Figure6 Such profiles and patterns can be used for comparison and/& identifieaiion of man; types of evidence.] ~
~
.~
~~~~~~
Figure 4 rlaptoglobln prof les from o &stains. Haptogloo ns. a group of glycoprmem that omd hemog ooin n the oiood, occur in each person's o ow 8s one of three possible phenotypes. Hpl, Hp2, or Hp2-l (in addition, there are rarely occurring variant phenotypes). Separation ot a protein extract from a dried bloodstain using polyacryiamide gel electrophoresis (a technique that Separates proteins according to their molecular charge and molecular size) yields a discrete panern of protein bands tor each phenotype. This figure shows the banding panem of the three common phenotypes and a Hp2-1M variant. Counting from the lsll, the first, second, and sixth columns show that the panerns obtained bom mixing blwds of different phenotypes (eg., Hpl and Hp2-1 in column one) can be distinguished from blood from a single individual. The haptoglobin bands are made visible (*om among the many Other protein bands which may have been separated also) by using a staining system specific for me bound hemoglobin.
Figure 5. Gunshot residue deposition. This photograph shows the cloud of gunshot residue (GSR) emanating tram lhe discharge of a revolver. The tiring of an automatic-loading handgun usually deposits even more GSR on the shooting hand from the large cloud of GSR released *om the ejection port of the weapon during the release of the cartridge case.
1056
Journal of Chemical Education
Figure 6. Comparison of gunpowder by gas chromatography/mass spectrometry (GCIMSI. The upper figure shows the profile of organic compounds extracted from Norma N-200 smokeless gunpowder. From their mass spectra. the peaks were identified as follows: 191. nitroglycerin; 246, 2.4dinltrotaluene; 275, diphenylamine: 303. 2.4,6trinitrmoiuene; 428, 444, 459. and 606. diestem of phthalic acid. All of the spectra from the peaks can be combined into a single, summed spectrum (lower figure) which can then be computer-matchadagainst a ilbrar, 01 known gunpowders. in the summsd-mars spectrum, one can see the major ions of the individualcomponems: 46.76, nitroglycerin: 89,165, 2,rldinitotoluene: 167,168.169. diphenylamine; 89,210. 2,4,6trinitrotoluene: alxj 149. ehthalate esters.
