Members of the Department
Nigel Hodge BSc. BTh. DipPS. >
John Page. BA. MSBiol. CBiol. PGDip. >
Dr Sara Short BSc. PhD. MFSSoc. MAE >
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Dr Neil Simpson BSc (Hons) D. Phil. >
Charlotte Spires
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Mark Webster
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Forensic Biology is the application of biological analytical methods to legal investigations. It involves the examination of evidential items and/or scenes of crimes for different body fluids, hairs, fibres etc which could link certain individuals to those items or locations.
There are several types of bodily fluid that may be found at a crime scene or on the clothing of a victim of a crime, which have the potential to be analysed and used to help identify the perpetrator of that crime. Bodily fluids fall into two categories, namely excreted fluids e.g. faeces, vomit, bile and sebum (skin oil) and secreted fluids e.g. blood, semen, female ejaculate, saliva and urine.
Blood Pattern Analysis (BPA)
The presence of blood at a crime scene at a crime scene indicates some form of physical struggle, assault or murder took place. However, analysis of the distribution of that blood at the scene (bloodstain pattern analysis) or on the suspects and victims clothing and other items can assist in determining who participated in the attack and who was just a bystander or who assisted the victim after the event.
Bloodstaining on items or individuals can be deposited in two ways, namely contact between surfaces and airborne deposition.
Contact bloodstaining arises as a result of two surfaces coming into contact with one another while one of the surfaces bears wet blood. Some contact stains can show details of the object that made the mark such as the pattern of fabric or hair. Smeared contact stains arise as a result of a moving contact between two objects, one of which is wet with blood.
Airborne bloodstaining arises as a result of wet blood becoming airborne, due to the application of force. The direction of travel of the blood can often be determined by conducting blood pattern analysis and the examination of the shape of the bloodstain.
Examples of airborne bloodstaining include:
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Impact spatter, which is often seen in cases involving assault.
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Passive drips, which come from blood falling under gravity from a source of wet blood i.e. the wound of a victim.
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Cast off, which is typically found in cases involving multiple stab wounds to a small area of the torso or blows from a blunt object to the head of a victim.
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Expirated blood, which results in blood in an airway of a victim (such as the mouth or nose) being expelled by the passage of air.
Blood transfer may be primary or secondary. Primary transfer occurs when an object wet with blood comes into direct contact with another surface. Secondary transfer occurs when an object wet with blood comes into contact with another object which then comes into contact with a third object , transferring wet blood in each case. When an assailant becomes blood stained, as a result of striking someone, blood is transferred directly from the complainant to the assailant i.e. there is primary transfer. If the assailant then touches a door handle with their now blood stained hands that represents secondary transfer.
Blood pattern analysis - case example
An altercation between a group of youths and a single male occurs in the street. This results in the male being stabbed and fatally wounded. The victim’s blood is deposited on the clothing of all of the youths and they are all subsequently charged with murder. The murder weapon (a knife) is later recovered but no DNA apart from that of the victim is recovered from it.
How can our forensic biologist assist the defence counsel?
Our forensic biologists have years of experience in blood pattern analysis (BPA) having given blood pattern analysis evidence and appeared as expert witnesses in many serious and high profile cases.
Our forensic biologist can:
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Re-examine the clothing or other items from all of the defendants.
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Review the origional blood pattern analysis findings and report of the Crowns forensic statement.
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Re-examine the blood pattern evidence previously examined by the prosecution as well as conducting new analysis on other items which may not have been initially submitted but which may be of significant evidential value even by their omission.
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Re-interpret the evidence to see whether the blood deposited on their clothing is consistent with them being the knife wielder, somebody who also assaulted the victim or just a bystander to the assault and subsequent murder.
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Examine the prosecutions interpretations and submit new interpretations of the blood patterns in question.
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Provide a detailed forensic expert witness report commenting on all issues raised by the defence counsel together with expert opinion on any other aspects found to be relevant to the defendants case during our investigation.
Body Fluid Analysis
Conducting body fluid analysis in order to determine the presence or absence, identity and distribution of particular body fluids is key to the investigation of crimes against the person e.g. rape, assault or murder. The body fluids encountered in these types of cases are usually blood, semen and saliva and in some cases given the severity of the crime urine and faeces.
The correct identification of traces of these fluids at a crime scene or on clothing may be vital to a criminal investigation. The presence or absence of a particular body fluid on clothing, possible weapons, swabs or other items related to a crime scene, may assist a forensic biologist in determining what may have occurred at a crime scene and in identifying the persons that were or were not involved in the perpetration of the crime.
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Body fluid analysis - case example
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A man is arrested and charged with rape, having been accused by a work colleague who said that he raped her, following an after-work drinking session. He admits to being intimate with her after having too much to drink, but denies that any penetrative sexual intercourse ever took place.
How can our forensic biologist assist the defence counsel?
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Our forensic biologists have many years of experience in testing and analysing the following body fluids:
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Blood analysis
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Semen analysis
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Saliva analysis
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Sweat analysis
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Vaginal material analysis
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Urine analysis
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Faeces analysis
Our forensic biologists can:
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Review the findings of the prosecution scientist, if one has been involved.
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Re-examine the clothing of the accused and the victim, in the light of any DNA results obtained, to try to determine whether or not any DNA found can be directly attributed to the key body fluid of the accused, in this case semen.
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Analyse the distribution of any body fluids found on the clothing of the alleged victim and the accused to see whether or not it coincides with the victim’s or the accused version of events.
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Appear as an expert witness should the case go to trial, where they will ensure that the true value of the prosecution’s evidence is explained in a clear and credible manner, with other possible interpretations put forward for the benefit of the court.
Clothing Damage Analysis
In cases of crimes against the person such as rape, assault or murder, clothing damage analysis or the damage analysis of other items may provide evidence to support or refute a particular alleged sequence of events, in relation to a particular crime. An important part of the investigation of assault cases relates to how the damage to the clothing of those involved occurred.
Microscopic examination of damage to garments can often distinguish between cutting, slashing, stabbing and tearing and recent damage may be distinguished from normal wear and tear. It may also be possible from the nature of the damage to determine the characteristics of the implement that caused the damage and weapons suspected of being involved in a particular incident can be tested, to see if they produce damage similar to that seen on the garment under investigation.
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Forensic analysis - case example
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After a night out drinking with a group of male and female acquaintances, one of the females wakes up in hospital after suffering a memory blackout and believes that one of the males in the group may have raped her, while they were left alone together in an alleyway. Witnesses suggest that they saw a male, believed to be the defendant, struggling with a woman and forcibly removing her clothing in that alleyway. The accused man denied rape but admitted to consensual sex with the complainant. He also claimed that she tore her dress earlier in the evening when she caught it on a protruding nail in the toilets of one of the bars they had been drinking in. Vaginal swabs were taken from the complainant but no semen was found on them. The clothing of the complainant was not submitted for forensic examination.
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How can our forensic scientist assist the defence?
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Our forensic experts have many years of experience in analysing damage to clothing and other items to try to ascertain how that damage occurred and what type of implement caused it. They are also experienced in carrying out controlled tests on suspect weapons to see if they could have caused the damage in question. Our forensic scientist can:
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Examine the clothing that the complainant was wearing at the time of the alleged rape for any damage
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Microscopically examine any damage found to ascertain whether or not it was consistent with tearing caused by forcible removal of that clothing.
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If the damage was unlikely to be caused by manual tearing, to suggest how else it may have occurred and to explore the possibility that it could have been caused by a protruding nail as alleged by the defendant.
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If the location and nature of the nail can be ascertained to compare the clothing damage with control damage made by a nail of a similar type.
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Provide an extensive report addressing all the issues raised by the defence council along with anything else found to be relevant to the defence case.
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Appear as an expert witness where they will ensure that the true value of the prosecution’s evidence is explained in a clear and credible manner with other possible interpretations put forward for the benefit of the courts.
DNA Profiling
The recovery, analysis and profiling of DNA recovered from crime scenes has become crucial to the detection and prosecution of perpetrators of crime. DNA profiling has the potential to uniquely identify an individual from traces of body fluids, hairs or skin cells left at the scene or recovered from items related to the incident. However, if a DNA profile is made up of contributions from a number of individuals or from an unidentified body fluid or only a partial profile is obtained, then the results may be open to a number of possible interpretations.
As the sensitivity of DNA technology has increased so too has the ability of forensic scientists to detect ever decreasing trace amounts of DNA. Therefore, it is necessary to consider the circumstances surrounding the collection of a DNA sample and how the DNA profile was obtained. It is also crucial to consider when and how that DNA evidence could have been deposited on the item under investigation.
It is therefore very important that DNA evidence is peer reviewed by a forensic scientist who is highly experienced in that specialist area.
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How can our DNA profiling experts assist the defence counsel with the DNA evidence issues?
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Our DNA profiling experts have very substantial experience and expertise in the application and interpretation of DNA collection and DNA evidence.
Our forensic scientists can:
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Review the findings of the prosecution scientist, if one has been involved.
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Consider the circumstances surrounding the collection of a particular DNA sample with particular reference to continuity and integrity of the items under investigation including such issues as cross contamination and/or secondary transfer.
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Comment on when and how the DNA evidnece in question may have been deposited on the item it was found on and how that impacts on the evidential significance of finding DNA with that particular profile on that item.
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If required, appear for the defence counsel as an expert witness, providing expert witness testimony capable of withstanding even the toughest cross examination.
Forensic Fibres Analysis
Forensic fibres analysis often assumes an important role in any crime scene investigation. Fibres are often regarded as the most common and integral part of evidence located at the scene of a crime. They can give intelligence on the perpetrator of a crime, what that person was wearing at the time and also what sort of contact there was between the perpetrator and the victim.
Most items of clothing are made out of tiny fibres almost invisible to the naked eye and when two people come into contact those minute fibres may be transferred between them. There are three basic fibre groups: vegetable fibres (cotton, flax and linen) animal fibres (wool) and man-made fibres (polyester and nylon).
Fibres evidence
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Connecting a suspect to a crime by collecting and analysing trace evidence like fibres is a very specialised undertaking and fibres which appear very similar in colour to the naked eye can often be discriminated by a fibres expert using their specialist expertise and a series of forensic instrumental tests. The presence of ‘foreign’ or non-constituent fibres on clothing has played a key role in many criminal convictions. However, as with all types of trace evidence, issues continue to be raised about potential cross contamination of items in the aftermath of a crime.
The position of fibres and the way they have been deposited on a surface can also provide intelligence as to what may have happened at a crime scene. For example if fibres are found in balls on the surface of a carpet, it may indicate that something heavy (such as a dead body at a murder scene) had been dragged across it forming those fibrous balls.
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Forensic fibres analysis - case example
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A woman is discovered in her bedroom, having been strangled to death. Her clothing is sent to a forensic laboratory for examination for trace evidence including fibres. ’Foreign’, non-constituent fibres which are navy blue in colour are found on her clothing. Clothing seized from a suspect includes a navy blue woollen jumper and the Crowns forensic scientists report indicates that the fibres in the jumper are similar to those found on the victims clothing. Issues are raised pre-trial about possible contamination issues surrounding the murder scene as the first person at the scene was also wearing a navy blue woolen jumper and no protective clothing.
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How can our forensic fibres analysis expertise assist the defence counsel?
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Our fibres experts have years of experience in recovering and examining fibre evidence and in interpreting its significance. We can:
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Review the Crowns fibre evidence and forensic report.
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Re-examine the victims clothing, the fibres previously recovered from the victims clothing and the suspects clothing and reassess all the fibre evidence.
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Examine the navy blue jumper worn by the first person at the scene to see if that jumper could have contributed in any way to the navy blue foreign fibres found on the victims clothing.
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Appear for the defence council as an expert witness where they will ensure that the true value of the prosecution’s evidence is explained in a clear and credible manner with other possible interpretations put forward for the benefit of the courts.
Forensic Hair Analysis
Hairs are another form of trace evidence which are often found at crime scenes and forensic hair analysis is the study of such evidence. Physical contact between people may result in head, body or pubic hairs being transferred from one person to another. Hairs may be found adhering to broken glass or woodwork at the point of entry at a burglary scene.
Forensic hair analysis and the examination of hair roots can be important when investigating violent crime. The appearance of the root will differ depending on whether the hair fell out or whether it was pulled out by force. It may also be possible to determine if hair has been burned cut or crushed. Forensic hair examination can also provide information about racial origins. Hair which has been died may also prove characteristic of a particular suspect.
If the root and sheath material are still adhering to hairs then they can also be used for DNA profiling and compared to a DNA reference sample from a suspect.
Hairs which are suspected to originate from animal sources can also be examined and attributed to a particular species of animal (e.g. dog, cat, rabbit etc.) or if they are unusual or multi- coloured they may indicate a particular variety (e.g. Siamese cat).
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Forensic hair analysis - case example
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The body of a murdered person is found dumped in woodland. A suspect (the owner of a large black and tan German Shepherd dog) who was known to the victim is apprehended. The clothing of the victim is sent to a forensic laboratory to recover any trace evidence from it and tan animal hairs are recovered from that clothing. The prosecution case is that the victim was carried to the woods in the back of the suspect’s estate car, the carpet of which was covered in hairs from his dog.
How can our forensic scientists assist the defence counsel?
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Our experts have years of experience in examining hairs both human and animal. We can:
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Review the forensic findings of the prosecution in respect of the hair evidence.
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Re-examine the hairs recovered from the victims clothing to confirm or refute that they are dog hairs and whether or not they could be fox hairs, as the body was dumped in woodland.
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Conduct a secondary forensic hair analysis to compare the hairs from the suspects dog to those recovered from the clothing of the deceased and if they prove to be similar, comment on the strength of that evidence (e.g. does that similarity mean similar coloured dog, same type of dog or the particular dog owned by the suspect).
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Provide a detailed forensic expert witness report commenting on all issues raised by the defence counsel together with expert opinion on any other aspects found to be relevant to the defendants case during the investigation.