Reconstruction of crimes by infrared photography

Abstract

Whenever blunt or sharp forces are used in a crime, analysis of bloodstain pattern distribution may provide important information for the reconstruction of happenings. Thereby, attention should be paid to both the crime scene and the clothes of everyone involved in the crime. On dark textiles, though, it is difficult or even impossible for the human eye to detect bloodstains because of the low contrast to the background. However, in the near infrared wavelength range, contrast is considerably higher. Many textiles reflect light beyond a wavelength of 830 nm and thus appear light-colored, whereas blood absorbs the light and appears dark. In our studies, a D7000 NIKON reflex camera modified for infrared photography produced high-resolution photographs visualizing even very small spatter stains on dark textiles. The equipment can be used at any crime scene or lab and provides immediately available and interpretable images. Thus, important findings can be obtained at an early stage of police investigations, as two examples (homicide and attempted homicide) illustrate.

Degrees of contrast: Detection of latent bloodstains on fabric using an alternate light source (ALS) and the effects of washing

“…This study found IR is a viable option when looking for blood on dark fabrics and often performs better despite the maximum absorption of blood being around 410 nm. This is because the fabric reflects the IR light at about 830 nm and we are left with a gray to white background and a dark in color stain [5]. However, when searching for blood on new clothing there are chemical additives that may alter the appearance of blood under ALS.…”

“…Current literature reports that blood experiences the greatest absorption of light around 410 nm and will appear much darker than its surrounding fabric [2][3][4]. Research shows that fabrics reflect light that is greater than 830 nm [5], so IR can be an incredibly valuable wavelength when searching for evidence. IR has been discussed in forensic science books since 1961 but was not widely used until the digital era because the film was expensive [6].…”

3D Crime Scene Investigation

“…This is a kind of operation which is very easy and there are different types of systems there through which it can be used (Kanbar, 2016). There are two ways which are called the basics like stitching and the exporting which can be done in an automated way (Sterzik and Bohnert, 2016). There are two things which are called as the indication and the distortion which can be minimized with the use of the smart software.…”