The forensic use of luminol chemiluminescence to detect traces of blood inside motor vehicles

Abstract

The luminol test for blood was carried out on a set of interior fittings and surfaces inside three different makes of modern motor car. The surfaces and fittings provided little interference with the test for blood, although there was some detectable chemiluminescence when the test was applied to blood-free material from a seatbelt, a boot-lining and a gear-knob. The case with which haemoglobin samples could be washed off interior car surfaces was also examined for seat fabrics, carpets, roof-linings and various other plastic interior surfaces. A standard wash with water alone was not very effective and removed only ca. 50% of the haemoglobin. A standard wash with soapy water or with a proprietary multipurpose car cleaner removed ca. 90% of the haemoglobin from the tested surface. The effect of high car interior temperatures on haemoglobin samples that were subsequently used in the luminol test was also examined. It was shown that the sensitivity of the luminol test was not decreased but was increased by the prior heating of a haemoglobin sample. This effect was attributed to the thermal conversion of haemoglobin to the more brighter catalyst for chemiluminescence, methaemoglobin. The enthalpy of this conversion in the solid state was found to be 14.1 kJ/mol.

Detecção de manchas de sangue pelo luminol onde houve entintamento das paredes – estudo de caso

“…A análise do padrão das manchas de sangue como a distribuição, forma, contorno e tamanho pode substancialmente contribuir na reconstrução de eventos em cenas do crime [11]. O luminol se mostrou eficiente mesmo quando a quantidade de sangue é diminuta [12] como no caso da parede analisada.…”

Selected Issues of Collecting Forensic Evidence with a Mobile Robot

“…During the investigation of some types of the crime scenes, a need to search for some biological evidence such as blood is likely to occur [9]. When found, blood traces are documented by forensic technicians with a camera.…”

“…After this period the intensity of the illumination is too weak to notice. Due to the fact that the luminol solution reacts only with a part of the blood cell components, the discovered blood can be afterwards used for ABO blood group tests [9,[11][12][13]. Negative aspects of the use of the luminol solution in the process of searching for the blood stains are related to the nature of the oxidation process and the interferences of some chemical compounds.…”

Improving Luminol Blood Detection in Forensics

“…Although the classical luminol protocols by Grodsky and Weber are good enough in most cases, some attempts were made recently to improve the reaction , in several instances the final results being applied in commercially available kits.…”

“…In 2004, Quickenden et al noticed that blood stains which are found in vehicles gave a stronger luminescence with luminol compared to the blood stains from outside the vehicles. They suggested that methemoglobin was involved in this enhancement process, as Fe 2+ oxidation could occur faster in a warmer environment.…”