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Technique for Processing Carbonless Documents (This technical report is reprinted from the recent March/April 1999 issue of the Journal of Forensic Identification, vol. 49 #2, pp 122 -- 124. Thanks to Kurt Kuhn, Beverly Hills Police Department for suggesting this article.)
by HELEN MARQUEZ The Internal Revenue Service, Criminal Investigation Division, is charged with investigating tax fraud and other tax related crimes. Special agents from the Criminal Investigation Division submit many tax related documents to the laboratory for latent print examination. Carbonless documents, such as W--2 form, require special handling to preserve the carbon entries. Many times the carbon impressions would run or wash away entirely when the evidence was processed conventionally. Occasionally agents who submitted evidence would request that this type of evidence not be processed for latent fingerprints for fear of losing the information on the documents. Faced with this predicament, personnel of the Latent Print Unit believed it was necessary to develop a safer, less destructive method of processing these exhibits for latent fingerprints. After experimenting with different techniques [l], an indirect method of processing which keeps the evidence dry proved to be the most successful. The procedure for this indirect method of processing begins with placing the ninhydrin working solution in a glass tray. The ninhydrin solution is prepared as follows: 200ml ethyl alcohol -- 200 proof (absolute) 25 g ninhydrin 4 liters of heptane Next, two sheets of blotter paper are dipped into the tray to absorb the solution. The blotter sheets are removed and allowed to dry. The carbonless document is placed between the blotter sheets. The package is placed in a dry mount press at a temperature of 200 degrees Fahrenheit for 30 minutes. After 30 minutes in the dry mount, the document should be removed from between the blotter sheets and placed in a humidity chamber for one hour to expedite development time.
This indirect method of processing documents with carbon impressions allows the document to be processed without the undesirable running or fading which often resulted when this type of evidence was processed in the conventional manner. Now these documents that were often omitted from examination can be processed safely. The value of this technique has been confirmed over and over again in a number of cases. Note: When working with chemicals, standard laboratory safety procedures should always be followed. For further information, please contact:
Helen Marquez Reference 1. Bratton, R; Juhala, J., “”DFO--Dry's, Journal of Forensic Identification, 45(2), 1995, p 169.
This article was printed in “THE PRINT” |