Biologia forence

TECHNICAL NOTE

J Forensic Sci, March 2006, Vol. 51, No. 2 doi:10.1111/j.1556-4029.2006.00065.x Available online at: www.blackwell-synergy.com

Nicholas Vandenberg,1 B.Sc. (Hons) and Roland A. H. van Oorschot,1 Ph.D.

The Use of Polilights in the Detection of Seminal Fluid, Saliva, and Bloodstains and Comparison with Conventional Chemical-Based Screening Tests

ABSTRACT: Biological stainscan be difficult to detect at crime scenes or on items recovered from crime scenes. The use of a versatile light source may assist in their detection. The ability of Polilights to locate potential semen, saliva, and blood stains on a range of substrates and at different dilutions was tested. We also tested the use of Polilights in comparison with conventional chemical-based presumptive screeningtests such as acid phosphatase (AP), Phadebass, and luminol, often used in casework for detecting potential semen, saliva, and blood stains, respectively. The Polilights was able to locate stains that were not apparent to the naked eye. The color of the material on which a stain is deposited can have an effect on the detectibility of the stain. The Polilights was found to be comparable with the APand Phadebass tests in terms of its sensitivity. In a comparative study between the AP test and Polilights on 40 casework exhibits, one false-negative result was observed when using the Polilights. On a series of mock casework exhibits it was determined that the Polilights can be used successfully to locate saliva stains for DNA analysis. The sensitivity of luminol for detecting potentialbloodstains was greater than that of Polilights; however the Polilights has particular application in instances where a bloodstain may have been concealed with paint. Overall, the Polilights is a relatively safe, simple, noninvasive, and nondestructive technique suitable for use in forensic casework. KEYWORDS: forensic science, forensic biology, alternate light source, Polilights, fluorescence, acidphosphatase, luminol, Phadebass

Detection of seminal stains on items such as clothing and bedding can be of significance in sexual assault cases. Similarly, locating potential saliva or bloodstains on clothing or at crime scenes can also assist investigations. Polilights is a versatile light source that produces intense narrow bands of light, at wavelengths between 310 and 650 nm. Polilights hasapplication in latent fingerprint detection (1) and may offer an alternative to other more commonly used chemical-based screening tests for biological fluids, such as the acid phosphatase (AP) test for seminal fluid, Phadebass paper for saliva, or luminol for blood. Polilights can potentially provide a rapid, less labor-intensive, presumptive screening test, particularly for large surfaces, beforefurther tests are used to confirm the presence of spermatozoa or blood. In 1991, Stoilovic (1) demonstrated that the excitation spectrum of semen was broad (i.e., fluorescence could be generated using wavelengths from 300 to 480 nm) and that blood had a strong narrow absorption band around $ 415 nm. These properties of semen and blood can be exploited to enable their detection (1). However, to date, thereremains an apparent dearth of literature on the application of alternate light sources (such as Polilights) for detecting biological fluid stains. One previous study, however, using a PL 10 (Rofin, Dingley, Australia) identified that the most significant factor in the detection of semen stains using fluorescence is the nature of the maVictoria Police Forensic Services Center, Macleod, VIC 3085,Australia. Received 4 June 2005; and in revised form 5 Sept. 2005; accepted 1 Oct. 2005; published 13 Feb. 2006. Copyright r 2006 by American Academy of Forensic Sciences
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terial on which a stain may be deposited (2). This study reported a degree of difficulty in detecting seminal stains on materials that were either highly absorbent, dark colored or were made of material that itself demonstrated...