Red stains on trousers

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The item was received in lab N804 at 9.05 am. The purpose of the examination was to look for any evidence present on the item. Before the examination was carried out the correct lab attire was put on (lab coat, gloves) and the bench washed down with ethanol. Brown paper was then laid on the desk, shiny side up to allow any fibres and other evidence which falls off to be easily spotted. The item was contained in an unsealed plastic bag and had no label on it. The bag was opened with a scalpel and the item placed on the brown paper. The item was a pair of light brown trousers made by 'Dockers'. The trousers had a waist size of 81cm (32 inches) and were 110cm long.

On the trousers there were red stains on the front. One on the crutch and six on the right hand leg. There were what appeared to be a hair and a fibre on the left hand leg and a hair in the creases near the waist band on the left hand side. On the rear of the trousers there was a further red stain on the left hand leg and a stain on the right hand leg which was only visible under UV light with a wavelength of 430-470nm. No evidence was found on the inside of the trousers. The examination finished at 11.40 am and the item was sealed in its bag.

Materials and Methods

The item was first examined using light examination to locate any possible evidence. This was done first with the naked eye and then with a magnifying glass with light fitting. Eight areas of staining and 3 fibres were identified and marked on the diagram.

The red stains were presumptively tested for blood using the Kastle-Myer test as mentioned in Johnson et al (2008). This gives an indication whether the stain is blood or not. They were then tested using the Takayama Confirmatory test as mentioned in Wael et al (2008). This confirms or disproves that the stain is blood.

The hair and fibre samples were examined under a microscope and their morphology compared to reference samples as mentioned in Birngruber et al (2009). This was done to identify what each fibre was and the possible source of the hairs.

The item was then examined under UV light, with wavelengths 400-430nm and 430-470nm, to look for any biological evidence which is not visible under white light. The stains visible under UV light where then tested for semen using the Acid Phosphate test, as mentioned by Virkler and Lednev (2009a). They were also tested for Urine using the DMAC test as mentioned in Virkler and Lednev (2009b)


My results show that the red stains on the front and back of the trousers are blood. The stain that's only visible under UV light is neither semen nor urine. The two hairs found are probably human and the fibre is Nylon.

What Next

As the hair samples do not have roots attached and therefore they are not very useful for DNA analysis (Birngruber et al ,2009). The hair was sent off for the morphology to be compared to suspect samples. The hair was also sent off for drug analysis using GC-MS to see if the person they belong to has a history of drug abuse (Tsanaclis and Wicks, 2007). The blood samples were sent off for DNA analysis to identify who it belongs to. This will be done by extracting using an extraction kit, such as QIAamp and amplified using a SMG plus PCR kit (Clark et al, 2009). The fibre was sent for further analysis to confirm that it is Nylon and to try and match it to any samples found from a suspect and the victim. This will be done by using microscopic techniques as well as chromatography of the dyes. (Jackson & Jackson, 2008)


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