Comparison of laser and mercury-arc lamp for the detection of body fluids on different substrates

Abstract

The performance of two detection techniques for body fluids, the Spectra-Physics(R) Revealtrade mark portable forensic laser system and the mercury-arc lamp Lumatec Superlite 400, was evaluated with various biological stains on different substrates. Serial dilutions of neat, 1/10, 1/100 and 1/1,000 using fluid semen, saliva, urine and blood were applied on glazed tiles, glass, PVC, wood, metal, stone, formica, carpet and cotton. Apart from the fact that blood traces were not detectable with the laser, both light sources showed comparable results regarding their detection capability. Clear advantages of the Lumatec Superlite 400, however, are its lower size, weight, purchase costs and the possibility to operate this light source by battery.

Evaluation of semen presumptive tests for use at crime scenes

“…7 However, these light sources are only suitable for locating suspect stains rather than for presumptive testing.…”

Statistical Evaluation of Alternative Light Sources for Bloodstain Photography

“…However, within this wavelength region, there is a narrow absorption peak around 395–435 nm (maximum at 415 nm) that has an especially high absorbance . Therefore, as reported in the literature, several types of ALS that produce this wavelength of light have been used for bloodstain scanning or enhancement, such as the Poliray™ , Polilight ® , Lumatec Superlite 400 , and high‐intensity LEDs . Recently, IR imaging has also been reported to be effective in enhancing bloodstains that were invisible under natural light .…”

“…Recently, IR imaging has also been reported to be effective in enhancing bloodstains that were invisible under natural light (2,9). The enhancement of bloodstains using different ALS on several surfaces, such as cotton, metal, glass, dried leaves, wood, carpet, brick, and several types of fabric, has been reported (3)(4)(5)(6)(7)(8)(9)(10)(11). However, no statistical tests were used in those reports, with all focusing on identifying the maximum detectable dilution of bloodstains using the different ALS.…”

Body fluid identification in forensics

“…Using this device, semen was best detected using a range of 415-490 nm, and saliva was also detectable in 60% of cases. However, poor results were obtained when it was applied to dark fabrics and to fabrics which had been washed, although it had been reported that different types of fabrics showed similar results (9,10).…”