Chemical Detection of Latent Fingerprints Steve Clark, Michael N. Gluigley,' and James Tezak Chevron Science Center, University of Pittsburgh, Pittsburgh, PA 15260 Most people are familiar with fingerprinting from news reports, movies, or detective novels. More often than not, these media conjure up images of a crime scene investigator "dusting" for prints with a fmely divided metal powder. Although this method of detection is still used (131, mode m science and technology have provided a number of additional techniques capable of detecting latent, or chance, prints with a high degree of sensitivity. Modern Reagents Many reagents have been tested for their ability to react with substances found in the perspiration transferred to an object from the palms of the hands. Most methods involving the use of reagents in powder form or solution rely on a reaction between the reagent and the minute quantities of amino acids present in skin secretions.
Reagents for Latent Fingerprint Detection Reagent Established 2,2-dihydroxy-l,3-indanedione (ninhydrin)
Benzo[e]ninhydrin Benzo[qninhydrin Assorted ninhydrin derivatives 5-Methoxyninhydrin 4-Phenylspiro[furan-(2,3),1'-phthalanl-3,3'dione
(Fluorescamine)
Colorimetric Reagents Among the most wmmonly used colorimetric reagents are 2,2-dihydroxy-1,3-indanedione, better known as ninhydrin (&7) some ninhydrin derivatives (7-12) In addition to its straightforward use, ninhydrin has been used with various enzvmes that increase its sensitivity to amino acids 113,. ~ni~rovcrncnts in scnsirlvity have also been r e ~ o r t r dfor tht! combination of Ruhcmam's Purple (the reaction product of ninhydrin and amino acids) with selected metals to form fluorescent wordination products (14-16). F/uorogenic Reagents Some fluorogenic reagents have also been used to detect latent fingerprints because they can react with secreted amino acids to form fluorescent ridge patterns (1731). In fact, many fluorogenic reagents are potentially useful due to their application in the determination of amino acid concentration in solution. To date, however, their usefulness in the detection of latent fmgerprints remains unreported. These reagents include 4-fluoro-7-nitrobenz-2,1,3-oxadiazole
(NBD-fluoride) 5-dirnethylamino-l-naphthalenesulfonylchloride (dansylchloride) 4-N, N-dirnethylarninoazabenzene-4-sdfonyl chloride (dahsyl chloride) sodium salt of 9,10-dimethoxy-anthracene-2-sulfonic acid (DAS-Na) Chemical Abstract registry numbers for these reagents are listed in the table with references for those reagents that have proved to be useful in the detection of latent fingerprints. This article does not detail the rationale behind i d e n t i cation of fingerprints because many books (3234) and articles (3537) discuss them. I t is useful, however, to remember that fingerprints may be classified into the three 'Author to whom correspondence should be addressed. Current address: Department of Chemistry, Mellon Hall, Duquesne University, Piusburgh, PA 15282.
Reference
Iodine vapor 4-Dimethylamino-cinnamaldehyde
Anthranilic acid, anthracene 4-Chloro-7-nitrobenz-2,1,3-oxadiazole
(NBD-chloride)and derivatives
47
7 7, 8 9, 10
11 12 17, 18 17, 19-21 2-24 25 26 27-29 30 31
Potentially Useful 4-N,NDimethylaminoazobenzene-4-sulfonyi
chloride (Dabsyl chloride) 5-Dimethylamino-l-naphthalenesulfonyl-chloride (Dansyl chloride)
C.A. Reg. no. [56512-49-31 [605-65-21 [29270-56-23
9.1O-Dimethoxvanthracene-2-sulfonic acid sodium salt (DAs-~a)
[67850-39-61
basic pattern types shown in Figure 1.Approximately 60% of all fingerprints in a given population fall into the "loop" category, while 35% are "whorls", and 5%are "arches" (32). Experimental Investigatory work was performed using two reagents:
'NBD-chloride, which has already been established as effectivefor latent fingerprintdetection dansyl chloride, which we consider potentially useful In fact, dansyl chloride was found to provide superior results for this particular application. The reaction of the reagent with amino acids is shown in Figure 2. The high degree of fluorescenceis due to the substituted amine portion of the molecule. Procedural
Obtaining the Prints Ten milligrams of dansyl chloride (Fluka) was dissolved in 20 mL of acetone (Fisher). :The reagent solution was Volume 70 Number 7 July 1993
593
(a) WHORL
(b) ARCH
(c) LOOP
Figure 1. The three main classes of fingerprints. sprayed onto the surfaces of fingerprinted articles using a spraykit (Sigma). The optimum distance was judged to be 9-12 in. For example, the reagent solution was sprayed onto fingerprinted filter paper. Then the paper was heated in a n oven a t approximately 50 'C for 1min. Excellent resolution of fmgerprint ridge patterns was obtained when the prints were viewed under UV radiation. Developing the Photographs Photographs were taken using a n ordinary 35-mm camera (Canon TX)equipped with a 13-mm automatic extension tube and a 135-mm medium telephoto lens (Quantaray). A W lamp (Mineralight WGL-25 lamp) was used a s a source of shortwave (254 n m ) or longwave (365 nm) radiation. The lamp was placed so that reflected radiation
Figure 3 Photograpn ot a latent flngerpr nt tnat was sprayed wlth a 500-mgiL sol~lon of dansyl chlor de n acetone. heated, and vlewed ~ndershomave (254 nm) J V raolal on to ack and wn le f lm (TMAX400 Kodak) 118-sexposure,F4 aperture). did not interfere with the fluorescent print. (Alternatively, a filter that absorbs UV rahation but transmits the visible range may be used. For example, Kodak Wratten No. 2 A filter absorbs all radiation below 410 nm.) Two types of film, easily available from most camera stores, were tested: color film (Ektar 1000, Kodak) usine 118-s exonsure b l a s and whke film (TMAX-400 Kodak) using 112-s exposure
.
For both t v ~ e of s film. the camera awrture was set to its maxirnumum(~4), and excellent r e d t i w e r e obtained. Once the fineemrink are develo~ed.thev remain fluorescent under h i a d i a t i o n for an indefinite pried. (Some finrremrintn in the authors'laboratow are still clearlv visible several months after developme~t.)A photograph of a fingerprint developed and photographed according to the above description is shown in Figure 3. Acknowledgment The authors are grateful to Ms. Lisa A. Alzo for assistance in preparation of the manuscript. Literature Cited
Nonfluorescent
Highly Fluorescent
Figure 2. Condensation reaction of dansyl chloride with amino acids results in the formation of highly fluorescent dansylates. 594
Journal of Chemical Education
13. M e n d , E. R.;Euerse, J.; Ewrse,K; Sinor,T.W.; 29.99.
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14. b a r d , C. J.: M m , P A,; Sterna, M.; Warrener, R. N. J Forensic Sei. 1987.32, ra3,.
15. Meneel, R. E.; Bartscb,R. A.; Hallman, J. L. J. F m s i c S c i . 1990,36,25. 16. Menzel, R. E.; Mitchell, K. E. J Forenaic Sci. 1990.36.35. 17. Lee,H. C.; A W d , A . E. J. Pollee Sci. Administration 1978,7,333. 18. O h h , H.&p N e t &s. Insl. Pollee &i. 1876,20,46. 19. Mayer, S. W.;Meilleur,C.P.; Jmes,P. F. IdpnfifiafionNews 1W7,9,13. 20. O h h , H. Rep N o t RPs. Inst. Pollee Sci. 1818.31.75. d 1978,18.233 21. Mayer. S.W.;Meilleur, C. P;Jones, P F.II F o m i ~ S SOC. 22. Tmwell, F J. J Forensic &i. Soc. 1875,15(31, 189. 23. C o m r , C. M. Idenlifwfion News 1916.26.3. 24. Almog, J;Sasson,Y.;Anati,A. J Forensic Sci. 1979,24,431 25. Sasson,Y;Almog, J. J. Forens* Sei. 1978.23.852. 26. Almog, J.: Gabay, A. J.Forens* Sei. 1980.25.408.
27. W m e r , R. N.; Kobua, H. . l ; Stoilouie, M. F o m i e Sci In1 1083,23,179. 28. Stoilouic, M.; Warrener, R N.; Kobus, H. J. Forensic Sei Inf. 1984.24,279. 29. Almog, J.; Zeiehner, A.; ShiGula, S.; ScharS G.J . ForensicSci. 1987.82,685. 30. Cheng, S . G J.ForensieSci. 1988,33,527. 31. Pounds,C. A: Grigg, R.; Mmgkolauseavaratans, T. J. Forensic Sci. 1890,35,189. 32. Moenssene,A. A. F i w r p r i n t s and f h e h w ;Chiltm: Philadelphia, 1969. 33. Olsen. Sr,R.D. SmillFigerp,-int Mechanics: Chsrles C. Thomaa: Sprh@eld, IL, ,am A".v.
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