Forensic Science International, 31 (1986) 189-194 Elsevier Scientific Publishers Ireland Ltd.

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AN INTERESTING APPLICATION OF INFRA-RED REFLECTION PHOTOGRAPHY TO BLOOD SPLASH PATTERN INTERPRETATION

MICHAEL ANTHONY RAYMOND* and ROBERT LYNDSAY HALL

State Forensic Science Labomtory, 193 Spring Street, Melbourne, Vie. 3000 (Australia)

(Received September 26, 1985) (Accepted March 20,1986)

Summary

Infra-red reflection photography is commonly used in various aspects of forensic work including document examination, firearm residue detection and surveillance work. Its use in the visualisation of blood stains is less well documented. The nature of a recent homicide case in Victoria, Australia, made it imperative that the blood spray pattern and its direction be determined. The success of the technique in this case gives credence to the argument that every “violent” scene should be approached with this capability close at hand.

Key words: Blood splash; Infra-red reflection photography; Photography; Pattern

Introduction

Infra-red, like ultraviolet photography, is regarded as a specialist photo- graphic area. It should, however, be within the scope of a trained forensic photographer.

The basic requirements for infra-red reflection photography are a source of infra-red radiation, a film which is sensitive to infra-red radiation and a filter to ensure that only infra-red radiation reaches the film.

Infra-red radiation and visible radiation are often reflected and absorbed to different degrees by common natural and man-made objects. Thus it is possible for bloodstains which are plainly visible to the naked eye to be rendered invisible with infra-red. However, many dyes which absorb visible light of most wavelengths do not absorb infra-red radiation and therefore record as a light tone. In that instance, infra-red photography acts as a means of enhancing image contrast as blood stains absorb both visible and infra- red radiation.

The degree of success is dependent on the condition of the blood and on the region of the infra-red spectrum used when taking the photographs.

*To whom all correspondence should be addressed.

0379-0738/86/$03.50 0 1986 Elsevier Scientific Publishers Ireland Ltd. Printed and Published in Ireland

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Oxyhaemoglobin is relatively transparent in the near infra-red but increases in opacity as the wavelength increases [ 11.

Case report

In the case under discussion, (a homicide), the deceased had been killed by repeated blows with a hatchet to the face and head. The deceased had been reposing on a chocolate-brown modular suite (used as a bed) at the time. The prosecution needed to show the position of the defendant in relation to the deceased on the suite, at the time the blows were struck. They also needed to show that the deceased had been under the continental quilt to refute the story of the accused.

The blood stain spattering on the quilt had been absorbed into the mater- ial giving very little indication as to direction of spray travel. It was almost impossible to see the spots on the suite. In addition it was difficult to see some of the stains on the two-colour sweater worn by the deceased.

Materials and methods

Luminol chemiluminescence methods as described by Zweidinger et al. [ 21 were not favoured because of:

(i) The problems associated with the production of secondary spots; and (ii) The transient and destructive nature of the technique.

Thus infrared reflection photography was employed to effect the re- quired result.

Most infra-red sensitive films which are suitable for general purpose infrared photography will record radiation with wavelengths up to approxi- mately 900 nm. The speed rating of the film is usually quoted for use with a particular light source.

Many light sources which are used for visible light photography are also sources of infra-red radiation. Daylight and electronic flash units are parti- cularly efficient with the peak infrared emission of an electronic flash tube being at approximately 760 nm. Tungsten and tungsten halogen lamps have a peak infra-red emission at approximately 900 nm.

The film used was Kodak High Speed Infra-red film in 10.2 X 12.7 cm sheets. The film was developed in Kodak D-19 developer for 6 min at 20°C. The correct exposure was determined by experiment and indicated a film speed of approximately 400 I.S.O.

The camera was mounted on a tripod and a Kodak Wratten 88A filter was placed over the lens. The lens aperture used was f16. The source of infrared radiation was a Sunpak 100 J electronic flash unit which was operated at full power.

The exposure technique used was to open the shutter and “paint” the

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subject with infra-red radiation by firing the electronic flash unit a number of times during the course of the exposure. The flash was bounced from a low white ceiling from various positions around the subject in order to pro- vide diffuse illumination. In addition, several flashes were aimed directly at the subject.

The imaging of infra-red radiation by a lens is analogous to that of visible radiation with the exception that the refractive index of glass is lower for infra-red radiation than for visible radiation. This results in the image being formed further from the rear of the lens and must be compensated for, either by making a manual adjustment to the visual focus position of the lens or by using a small lens aperture to achieve maximum depth of field.

In our experience it is well worth initially appraising the potential viability of the technique using a black and white video camera fitted with a tube having infra-red sensitivity up to 900 nm. A suitable tube is the Ultracon made by Rediffusion. Most colour video cameras do not have sufficient infra-red sensitivity to achieve a usable result.

The video camera’s output may be linked either directly to a monitor and the result viewed contemporaneously, or to a recorder. The camera is operated with a Wratten 88A filter over the camera lens and the subject is illuminated using a suitable source of infra-red radiation such as tungsten lamps or daylight.

Fig. 1. Black and white photograph of blood stained modular suite.

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Fig. 2. Infra-red reflection photograph of suite shown in Fig. 1.

Fig. 3. Enlargement of centre bolster region shown in Fig. 2.

Fig. 4. Infra-red photograph of deceased’s two-tone sweater.

Although the video image lacks the resolution and contrast obtainable with black and white infra-red photography, the result is obtainable immedi- ately and large subjects can be rapidly examined to determine whether further action is warranted.

Results and discussion

The black and white photographs (Figs. 1 and 5) and the infra-red reflec- tion photographs (Figs. 2, 3 and 4) adequately depict the success of the technique. Figure 1 is a standard black and white photograph of the blood- stained modular suite. Figure 2 is an infra-red reflection photograph of the same suite and shows very well the heavy bloodstaining in the corner. Figure 3 is an enlargement of the centre bolster region illustrating the directional blood splash pattern. Figure 4 is an infra-red photograph of the deceased’s two-tone mustard and bottle-green sweater, where Fig. 5 is a black and white photograph of the same. The improved contrast over white light photography in this instance is clearly shown. These photo- graphs of the bloodstains were accepted by the court in Victoria, Australia.

Fig. 5. Black and white photograph of deceased’s two-tone sweater.

The full potential of photography across the ultraviolet-infra-red spec- trum region has ye_t to be realised by the forensic photographer. Consequent- ly it seems reasonable to expect greater diversification in this area and a greater role for “specialist” photography in the forensic arena.

References

H.L. Gibson, Photography by Infrared, Wiley Interscience, N.Y. 1978. R.A. Zweidinger, L.T. Lytle and C.G. Pitt, Photograph of bloodstains visualized by Iuminol. J. Forensic Sci., 18 (1973) 296-302. T.C. Krauss and S.C. Warlen, The forensic use of reflective ultraviolet photography. J. Forensic Sci., 30 (1985) 262-268. H.L. MacDonell, Bloodstain Pattern Interpretation, Laboratory of Forensic Science, Corning, N.Y., 1982.