Status of the U.S. Secret Service Ink Dating Program Jolm \V. Hargett and Lan)' F. Stewart Dedicated to Dr. nvlfgang Steinke on the occasion of his 60th birthday.
/. /rl!lvduction The Questioned Document Branch of Forensic Services Division (FSD) has thirteen examiners working in a wide variety of document related cases. Requests for Branch assistcnce <:~(e often received from foreign governments; U.S. Congressional committees; Federal, stale and local law enforcement agencies; and non-law enforcement agencies such as the U.S. Stale Department and National Institute of Health. One of the duties of the Questioned Document llranch is the maintenance of a writing ink reference collection and research in the field of writing ink identfication and do~ument age determination. Recently, a senior document examiner Chaired a task group for the American Society For Testing and Materials (ASTM), which developed ami published standards designed for use in forensic facilities performing writing ink comparisons (Steu:art 1991). The Questioneu Document Branch nets as the "Coordinating Laboratory for Matters Concerning Ink" for INTERPOL, and as such Chairs their international meeting discussions regarding forensic ink analyses (llargeu 1992). The U.S. Secret Service International Ink Library currently consists of over 7000 writing ink formulas. These are largely obtained from the manufacturers on a yearly basis with the understanding that strict control over any proprietary information is maintained. The inks date back to the 1920's and include formulas produced by European,..Asian, Australian and North American manufacturers. The standards are sampled, analyzed, cataloged. and stored in our facility for future comparison against questioned documents (Stewart and G11ertill 1991. Hargett 1990).
2. Methods All writing examinations performed by the U.S. Secret Service begin by classifying the writing according to the type of writing instrument that was used. This is uetennined through microscopy and analysis of the ink line. Inks arc classified into two groups; ballpoint and non-ballpoint. Once the questioned inks are classified, they must, Lhen, be compared or identified. Identification of the writing ink formula requires access to standards or a writing ink library. This library of inks must be complete to the extent that the likelihood of a false identification is negligible. Small pin-holes of ink and paper are removed for analysis. These arc extracted with either pyridine (ballpoint inks) or ethanol/deionized water 1 : 1 (non-ballpoint inks). The extracts are spoiled onto plastic-backed thin layer chromatogram
"Status of U.S.S.S. Ink Dating Program," J.W. Hargett and L.F. Stewart Presented at the Humboldt University, Berlin, Germany, April 2, 1993. Published in "Kriminalistik und Forensische Wissenschaften" 1994, No. 82, p.27-31.
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HARGITIT/STEWART
plates. The extracts arc dried and the plates are activated. Separation of the extracted inks is :lchieved by placing the "spotted" plate in a solvent tank containing a solvent system composed of ethyl acetate/ethanol/deionized water 70 : 35 : 30. The solvent travels up the plate by capillary action and begins separating the ink based on the component's relative solubilities in the solvent system. The resulting chromatograms are compared agninst the similar inks from the stored library plates. Any possible matches against the library are then compared side-by-side with the questioned ink on a high resolution glass-backed chromatogram plate. IdentificatiOJl is normally nchieved at this stage. However, the use of high pressure liquid chromatography or fourier transform infrared spectroscopy may be required. Once an ink formula is identified, records are examined to detennine the sales history of the matchillg ink. At this point, it may be possible to show a questioned document is not legitimate based on the use of an ink formula that did not exist on the date of the document.
If no conclusion can be reached concerning the document's authenticity, i.e_ the ink was available on the purported date of the document, we may attempt to provide information regarding "how long" an ink has been on the questioned document. Although, this can be accomplished by many methods, the technique generally use.d by this agency is called, 路路Relative Age Determination'.". As the name implies, the "age" of one questioned writing is compared against other writings for which the date of entry is not in question. This comparison is done by examining either the extent of dryness of the ink entries or the extent of dye fading (Brunelle and Camu 1987). Before conducting this type of examination, two requirements must be met: 1) There must be entries on the same or similar documents whose dates are not questioned that are the
80
70
60 Ratio of
Peak Arrests
SOL-------------------------0 24 12 48 36 Age of Ink (months)
Fig_ I: Age of Entry v. Extraction Ratio.
HARGETI/STEWART
29
same ink formula as the questioned entry, and 2) The questioned and non-questioned ink entries must occur on the same document or documents stored under the same conditions. This addresses concerns regarding the influence of paper as well as storage condition inconsistencies. lf these requirements are met, the analysis begins by identifying the ink fonnula by the standard method described earlier. The location(s) of comparison inks that are not in question must also be accomplished. Next, the "ease" of extraction of the questioned and non-questioned inks are compared. This is done through the use of weak followed by strong solvents, thin Jayer chromatography and subsequent dcnsitrometric analysis. A ratio is created by measuring the extraction extent at different extraction times. This method allows for mass independent analysis. Finally. a graph is produced depicting Age of Entry v. Extraclion Ratio (Fig. l). Once the chromatogram has been developed the various dye components can be compared to determine the extent of fading that has occurred. Other methods of "dating" documents are also being explored (Cantil 1988). These include methods utilizing "accelerated age" techniques. The re1iability of these techniques is being evaluated and at this time the U.S. Secret Service does not utilize the "accelerated age" techniques in our routine casework.
3. Computerization ofthe System Over the years there have been many changes in the storage and retrieval methods used with the ink library. An idea was developed in the late 1980's to assign numbers to the bands of color that \\'ere appearing on the chromatograms. Conceivably, these numbers could then be used in a searchable database (Stewart 1985-1990). Along these lines, the chromatograms were standardized to a separation distance of 4 em. A zero to nine number scale was adopted to signify a range of ten colors. The blue and black inks were all re-classified using this system. Data concerning the'ink regarding ink type, color, manufacturer, fluorescence and luminescence characteristics have been placed in a computer database. This infonnation has been coupled with data regarding the chromatogram and separation characteristics in four separate regions of the plate (Region I origin to 1 em, Region 2 = 1 em to 2 em, ecc.). This database is searchable by any or all of the parameters giving maximum flexibility of the examiner.
=
For example, an examiner could search the database for all black ballpoint pen inks that were highly luminescent, non-fluorescent in the longwave ultraviolet region and have a chromatogram that has a blue band in the region from 2 em to 3 em. The system would then provide data for every ink that meets those criteria for the examiner to review. The final step would require a side-by-side comparison of the questioned to the known inks.
4. Further Developments Because of the tremendous use of the ink library, we are experimenting with making the library of inks available through a telephone modem. This would be for the exclusive use of authorized law enforcement agencies. We have recently completed the installation of
30
IIARGh1T/STEWART
Table J: USSS International Ink Library Identification System
•••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••••• ***~******* USSS INTERNATIONAL JNK LIBRARY IDENTIFICATION SYSTEH ************** ******************************************************************************** MANUFACTURER FISHER * I:OLOR COOE '* 10 I.NO * 0 BLAC( BATCH.ND 12A LOT.NO FORHULA.NO * ALT.NO INTRO.DATE 0~/01/70 RECD.DATE • * 1 BRCtllN ···············****************************************** **** * 2 RED • ss y OUNCE 3 FM L COLOR 6 TYPE BP * * ••••••••••••••••••••••••••••••••••••••••••••••••••••••••• •••• * -4 YELLI1J * ABS A * 5 GREEN LUMJN N IR CHARACTERISTICS • * 6 BLUE IR.REMA.RKS UV N • 7 VIOLET * ULTRAVIOLET FLUORESCENCE TAG.REMAFIKS TAGGANTS * 8 CiREY *
..
******************•························~··~··············
SEQUENCE THIN LAYER CHROMATOGRAPHY SPOT COLOR PLATE REGION: SOL.FRONT scs SC4 76 ZONE 4 SC3 7767 ZONE 3 SC2 ZONE 2 ZONE 1 SC1 6 sco 6 ORIGIN
*
9 \.IHITE
*
***************** FLUORESCENT COLOR * LEGEND * y YES FCS * FC4 * N NONE * FC3 * T TRANSMITS * FC2 * A A9SORBS * * R RA~E EARTH • FC1 FCO • F FLUORESCENT *
66776776
..
············••***
REI4A~k'S
the library on an in-house bulletin board system. This system will allow authorized callers to phone via a telephone modem to our computer in Washington. Our computer will an,.wer and prompt the caller for an identification sequence and password. The caller will then be directed through a series of menus allowing the searching of qucstione<J. inks. The inks can be searched by any or all of the available information and the resulting "match" list can be provided as full page date of repetitive line printing. Either can be downloaded to a local printer. Once ri search is completed, electronic mail can be easily generated between the user and the Secret Service examiners. This mail could be used if additional information regarding an ik is needed, e.g. history, first date of production, last date of production, etc. This ink bulletin board is currently being evaluated at test sites both outside and within the United States. The first such test silcs were at the forensic facilities of the Berlin Police and the Bundeskriminahimt. Since that time the system has expanded to include the Royal Can:1dian Mounted Police and the Kantonspolizei Zurich. At the end of the evaluation period it is anticipated that additional sites will he implemented.
Zusammelifassu11g Zu den Aufgabcn der Dokumentenunlersuchung in der Abteilung fur Forcnsischc Dicnstleistungcn des United States Secret Service gehilren die Fortflihnmg der Schreibmittelsammlung und Forschungsarbeiten zur Schreibmittelidentifizierung und Dokumcntenal-
I IARGETI/STEWART
31
tersbestimmung. Zur Zeit enthall die Sammlung mehr als 7000 Schrcibmittcl aus dcr g:mzcn Welt. Die Mcthodcn dcr Untcrsuchung von Schrcibmittcln und die 路MUglichkcitcn dcr Altersschatzung von Schriftstiicken werden beschricbcn (U::isungsverhalten, Diinnschichtchromatographic, Densitometric). - Das System wurde computerisicrt und eine abruibare Datenbank entwickell. Eine telefonische Abfrage wird z.Z. erprobr.
Summary
One of the dutics"Df the Questioned Document Drunch is the maintenance of a writing ink reference collection and research in the field of writing ink identification and document age deteiTilination. The ink collection currently consists of over 7000 writing ink formulas produced in many countries. The methods of ink analysis and document age detennination (ink extraction, thin layer chromatography, densitometric analysis) arc described. The system has been computerized, and a searchable database created. Telephone access to the ink library from foreign countries is currently being tested.
References R.L.: Cantu, A.A.: A Cun-ent Evaluation of Current Ink Dating Techniques; J. Forcns. Sc., 路 Vol. 32, No.6, November, 1987 Cantu. A.A.: Comments on the Accelerated Aging of Ink; J. Forcns. Sc., Vol. 33, No.3, May, 1988 Hargett, Jolin lV.: The International Ink Library; ICPR, No. 425, July-Allgust 1990 Hargett, Jolm \V.: Status oflnk Analyses. lOth INTERPOL Forensic Science Sympo~ium, November 24-27, 1992, Lyon, France Stewart, Larry F. (Task Group Chairman): Writing Ink Comparisons. ASTM E30.02 (6.2.1)-91 Stewart, Larry F.; Fortunato, Su.1wz L.; Becker; JoAmz: unpublished work between 1985-1990 Ste11路art, Larry F.; Guertin, Srtsmz L: Current Status of Ink Age Determination; ICPR, No. 429, Mnrch-April, 1991 Bru~rel/e,