Blood residue

Last updated January 24, 2025

Blood residue are the wet and dry remnants of blood, as well the discoloration of surfaces on which blood has been shed. In forensic science, blood residue can help investigators identify weapons, reconstruct a criminal action, and link suspects to the crime.^[1] Analysis of blood residue is also an important technique in archeology.^[2]

Forensic significance

Blood constitutes about eight percent of a person's weight (normally about five liters), and it circulates near the surface of the skin. Almost all trauma to the body, therefore, results in the shedding of blood. Its red color makes it readily apparent at crime scenes, and its residues are very difficult to completely remove. Blood residue has even been recovered from 100,000-year-old stone tools.^[1]

Laboratory testing can reveal whether a substance is indeed blood, whether the blood is of animal or human origin, and the blood group to which it belongs. This allows investigators to include or exclude persons as perpetrators or victims. The antigens that allow blood group testing, however, deteriorate with age or improper storage.^[3] The DNA contained in blood, on the other hand, is less subject to deterioration, and allows near-certain matching of blood residue to individuals with DNA profiling techniques.^[3] Through bloodstain pattern analysis, information about events can also be gained from the spatial distribution of bloodstains.

Forensic procedure

Finding and documenting blood residue

Freshly dried bloodstains are a glossy reddish-brown in color. Under the influence of sunlight, the weather or removal attempts, the color eventually disappears and the stain turns grey. The surface on which it is found may also influence the stain's color.^[1]

Crime scenes are normally carefully searched for blood residue. Flashlights held at an angle to the surfaces under examination assist in this,^[1] as do luminol sprays which can detect even trace amounts of blood. Presumptive tests exist with which blood can be distinguished from other reddish stains, such as of ketchup or rust, found at the scene.^[1] The search includes areas beyond the immediate crime scene where blood might have been wiped off or bloody fingerprints left, such as towels or doorknobs. At outdoor crime scenes, bloodstains may be recovered from the ground or from plant surfaces.^[4]

The standard documentation of blood residue includes photographs and descriptions of form, color, size and position of each stain found. Overall photographs and sketches are also produced to show the relationship of the blood residue to other elements of the scene and to enable pattern analysis.^[4] Recently 3D imaging techniques have been tried for documenting and investigating bloodstains.^[5]

Collection and preservation

To collect samples for analysis, wet blood is collected with a syringe and stored in a tube with anticoagulant, or collected with absorbent fabric that is allowed to air-dry. Dried blood is scraped off with a blade, or collected with a moistened cotton-tipped applicator, a gel lifter or fingerprint tape.^[3] Bloodstained clothing and other items are generally wrapped in paper and shipped whole to the laboratory.^[3] To prevent deterioration, blood residue samples are stored under refrigeration and, in the case of stains, air-dried.^[4]

Related Research Articles

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Forensic science, also known as criminalistics, is the application of science principles and methods to support legal decision-making in matters of criminal and civil law.

A crime scene is any location that may be associated with a committed crime. Crime scenes contain physical evidence that is pertinent to a criminal investigation. This evidence is collected by crime scene investigators (CSI) and law enforcement. The location of a crime scene can be the place where the crime took place or can be any area that contains evidence from the crime itself. Scenes are not only limited to a location, but can be any person, place, or object associated with the criminal behaviours that occurred.

Trace evidence occurs when objects make contact, and material is transferred. This type of evidence is usually not visible to the naked eye and requires specific tools and techniques to be located and obtained. Due to this, trace evidence is often overlooked, and investigators must be trained to detect it. When it comes to an investigation trace evidence can come in many different forms and is found in a wide variety of cases. This evidence can link a victim to suspects and a victim or suspect to the crime scene.

Forensic identification is the application of forensic science, or "forensics", and technology to identify specific objects from the trace evidence they leave, often at a crime scene or the scene of an accident. Forensic means "for the courts".

Bloodstain pattern analysis (BPA) is a forensic discipline focused on analyzing bloodstains left at known, or suspected crime scenes through visual pattern recognition and physics-based assessments. This is done with the purpose of drawing inferences about the nature, timing and other details of the crime. At its core, BPA revolves around recognizing and categorizing bloodstain patterns, a task essential for reconstructing events in crimes or accidents, verifying statements made during investigations, resolving uncertainties about involvement in a crime, identifying areas with a high likelihood of offender movement for prioritized DNA sampling, and discerning between homicides, suicides, and accidents.

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Fingerprint powders are fine powders used, in conjunction with fingerprint brushes, by crime scene investigators and other law enforcement personnel to search for and enhance latent/invisible fingerprints that can be used to determine identification. This method of fingerprint development commonly referred to as dusting for fingerprints, involves the adherence of the powder particles to the moisture and sweat secretions deposited on to surfaces by the raised ridges on fingers, palms, or soles of feet designed for grip, called friction ridges. Furrows, representing the recessed areas, which lack fingerprint residue, do not retain the powder.

Forensic biology is the application of biological principles and techniques in the investigation of criminal and civil cases.

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The following outline is provided as an overview of and topical guide to forensic science:

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<span class="mw-page-title-main">Forensic footwear evidence</span> Crime scene analysis

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Rape investigation is the procedure to gather facts about a suspected rape, including forensic identification of a perpetrator, type of rape and other details.

Forensic serology is the detection, identification, classification, and study of various bodily fluids such as blood, semen, saliva, and urine, and their relationship to a crime scene. A forensic serologist may also be involved in DNA analysis and bloodstain pattern analysis. Serology testing begins with presumptive tests which gives the analyst an indication that a specific bodily fluid may be present, but cannot completely confirm its presence. Following the presumptive tests, confirmatory tests are done on the same sample to confirm what the unknown substance actually is.

Glove prints, also sometimes described as gloveprints or glove marks, are latent, fingerprint-like impressions that are transferred to a surface or object by an individual who is wearing gloves.

Contaminated evidence is any foreign material that is introduced to a crime scene after the crime is committed. Contaminated evidence can be brought in by witnesses, suspects, victims, emergency responders, fire fighters, police officers and investigators.

Forensic firearm examination is the forensic process of examining the characteristics of firearms or bullets left behind at a crime scene. Specialists in this field try to link bullets to weapons and weapons to individuals. They can raise and record obliterated serial numbers in an attempt to find the registered owner of a weapon and look for fingerprints on a weapon and cartridges.

Ludwig Tessnow was a German serial killer known as the Monster of Rügen and the Mad Carpenter of Rügen, who murdered four prepubescent children in two separate attacks in 1898 and 1901.

References

1 2 3 4 5 Robinson, James L. (2008). "Blood residue and bloodstains". In Ayn Embar-seddon; Allan D. Pass (eds.). Forensic Science . Salem Press. p. 152. ISBN 978-1-58765-423-7.
↑ Hortolà, Policarp (2002). "Red blood cell haemotaphonomy of experimental human bloodstains on techno-prehistoric lithic raw materials". Journal of Archaeological Science. 29 (7): 733–739. Bibcode:2002JArSc..29..733H. doi:10.1006/jasc.2001.0782.
1 2 3 4 Robinson, 154.
1 2 3 Robinson, 153.
↑ "Liquid Drops and Splatters Forensic Measurements Using Portable Zebraoptical Optoprofiler". www.zebraoptical.com.