Infrared Imaging of the Crime Scene: Possibilities and Pitfalls

Abstract

All objects radiate infrared energy invisible to the human eye, which can be imaged by infrared cameras, visualizing differences in temperature and/or emissivity of objects. Infrared imaging is an emerging technique for forensic investigators. The rapid, nondestructive, and noncontact features of infrared imaging indicate its suitability for many forensic applications, ranging from the estimation of time of death to the detection of blood stains on dark backgrounds. This paper provides an overview of the principles and instrumentation involved in infrared imaging. Difficulties concerning the image interpretation due to different radiation sources and different emissivity values within a scene are addressed. Finally, reported forensic applications are reviewed and supported by practical illustrations. When introduced in forensic casework, infrared imaging can help investigators to detect, to visualize, and to identify useful evidence nondestructively.

Use of Unmanned Aerial Vehicles in Crime Scene Investigations - Novel Concept of Crime Scene Investigations

“…LIDAR (light illumination detection and ranging) is a technology used in UAVs that uses UV-rays, visible rays and near infra-red light to image objects. Infrared imaging is suitable for a wide range of forensic applications [2]. It can image wide range of materials including metallic and non-metallic objects, aerosol, clouds and even single molecule.…”

Reconstruction of crimes by infrared photography

“…Photography in the near infrared range up from 830 nm, as performed in the two example cases presented, is a suitable method to visualize undiluted bloodstains on dark textiles. The method combines the already known advantages of material's different optical behaviors within infrared wavelengths [5,17] and excludes the disadvantages of technical limitations at the same time [1,2,6,12]. The method does not only allow documenting bloodstains in detail by high-resolution pictures but also analyzing their distribution.…”

“…Bloodstain pattern appearance, however, may differ greatly depending on which fabric or underground they are on. Several studies have been performed dealing with influences of drop volume, dropping height and impact angle [4,22], drying properties [16], heated surfaces [9], different fabrics [4], as well as dark fabrics [5][6][7]18]. Bloodstains on dark surfaces bring along a considerable difficulty because of low contrast to the surface bloodstains are difficult or even impossible to detect with the unaided human eye.…”

Thermal handprint analysis for forensic identification using Heat-Earth Mover's Distance

“…The amount of infrared radiation is affected by the temperature and emissivity, as described by Stefan-Boltzmanns law: [3]:…”

“…Although this technology is used in many areas, to the best of our knowledge, so far there is no related work using thermal imaging for biometrics-based forensic personal identification. We exploit the infrared thermography in extracting handprint for personal identification for following reasons: i) it expands target extent by capturing any object with a temperature above zero; ii) thermal handprint can be obtained regardless of illumination or direct contact [3], which is more robust than other visible light-based imaging; iii) it is cost-effective compared to the high-resolution camera used in extracting detailed features of fingerprint.…”