BIOLOGICAL FLUIDS EXPERT

Authoritative forensic expert testimony in the disciplines of DNA, bloodstain pattern analysis (BPA), STRmix and biological fluids.

A preliminary review can be a useful step in assessing the broad strengths and weaknesses of a particular matter. This process can also identify documentary and any further evidence requirements.

I rigorous interrogation of the evidence will uncover underlying issues and determine the most appropriate pathway towards reviewing and reporting the matter.

Certain complex matters benefit from a draft report, which can open areas for discussion with Counsel, and potentially allow for defence to approach the prosecution.

Following a thorough evaluation of the evidence, a DNA expert report will be issued in accordance with the expert witness code of conduct. The report will be suitable for submission in evidence.

Preparations with Counsel are often conducted, such that the probative value of the evidence is weighed effectively and persuasively at Voir Dire, should such a hearing be required.

Extensive preparations are generally conducted in anticipation of substantive hearing. Which may include cross examination and evidence in chief scenarios specific to the matter .

Robust scientific detection and classification of biological fluids is critically relevant to forensic evidence.

Biological fluids cannot scientifically, in and of themselves be relied upon as to identity.

DNA is suspended within semen, blood, urine and saliva, meaning it can be deposited along with the biological fluids.

Precise identification of the biological fluid type can be a crucial link between an individual and the alleged act itself, this alone can be determinative as to the inculpatory or exculpatory value of the evidence.

Laboratories frequently utilise subjective testing, which can presume the presence of blood, semen or saliva, for example. Subsequent confirmatory re-testing has been known, in cases, to reveal that no biological fluids are in fact identifiable.

Cells containing DNA are highly transient, meaning the presence of DNA in the absence of biological fluids, can be of significantly less evidentiary weight.

Robust scientific detection and classification of biological fluids is critically relevant to forensic evidence.

Biological fluids cannot scientifically, in and of themselves be relied upon as to identity.

DNA is suspended within semen, blood, urine and saliva, meaning it can be deposited along with the biological fluids.

Precise identification of the biological fluid type can be a crucial link between an individual and the alleged act itself, this alone can be determinative as to the inculpatory or exculpatory value of the evidence.

Laboratories frequently utilise subjective testing, which can presume the presence of blood, semen or saliva, for example. Subsequent confirmatory re-testing has been known, in cases, to reveal that no biological fluids are in fact identifiable.

Cells containing DNA are highly transient, meaning the presence of DNA in the absence of biological fluids, can be of significantly less evidentiary weight.

False Positive

Biological fluid false positives regularly occur with the use of presumptive testing.
Presumptive testing is the common method used by Australian laboratories and relied upon in the subsequent report.
Caution is advised to avoid any assumption that a presumptive test is conclusive.
Presumptive biological tests are convenient and low cost.
They can yield a false positive to other biological and non-biological matter such as vaginal fluid, faecal matter, blood, rust and bleach.
Interpreting biological fluid test results requires careful consideration by a skilled forensic scientist, to avoid any mis representation before the court.

Error Rate

The error rate in biological fluids evidence before the courts, spans two areas, which are interconnected.
Firstly, presumptive testing, is regularly relied upon to confirm biological fluids, when it should more appropriately be confirmatory testing that is relied upon.
Secondly and subsequently, the presumptive positive is relied upon to infer that the biological fluid (apparently identified) is connected to the individual by virtue of the entirely separate DNA likelihood ratio.
The relationship between given biological fluids and the DNA are regularly of critical significance in a matter. and require careful and highly skilled consideration.

Contamination

Biological fluid contamination can occur during medical examination, crime scene investigation and within the laboratory.
Appropriate anticontamination protocols should be strictly maintained.
Subtle means of body fluid contamination can occur between locations (transfer) of a particular item of interest. This can be of specific importance when the exacting location of the said body fluid is relevant to the confirmation or refutation of the alleged facts.
Contemporaneous notes from biological fluid examinations along with the DNA results, can adduce further information as to the likelihood and potential implication of contamination.

Bodyfluid Testing

Presumptive testing of biological fluids such as blood, semen and saliva are commonplace, and known to produce false positives.
Confirmatory testing should be conducted when the type or true existence of body fluid is critical to the facts of an alleged crime.
Accurate testing and interpretation of biological fluids as to the individual and type can contribute substantially to a matter.
The critical importance of body fluids testing is understood, when the erred testing of fluids negates the courts weighting of a robust DNA match within a matter.
Roebuck Forensics can conduct confirmatory testing on suspected biological fluids.

Crime scene examination

DNA and biological fluids are very commonly sampled together and subsequently inferred, and perhaps assumed to be a singular deposition.
Conjunctive evaluation of DNA and biological fluids as sampled, is not in all circumstances scientifically well founded.
DNA is regularly reported with the apparent inference, that it originates from the body fluid sample, when confirmatory testing reveals that no such inference is supportable.
The highly transient nature of both DNA and biological fluids dictates that very careful consideration should be applied to their combined relationship within the crime scene evidence.

Time since event

Time since event can be of critical relevance in sexual assault matters, as to the question of semen deposition.
Caution is advised when relying upon subjective testing of fluids.
A common scenario is one where ejaculation is alleged, though semen cannot be scientifically identified with confirmatory testing.
Internally deposited semen rapidly degrades in quantity and structure due to biological and environmental factors, with the likelihood of a true positive fading rapidly in the time since intercourse (TSI).
Deposited fluids can degrade rapidly over time due to environmental factors, with published data being useful in limited scenarios.
False positive

False Positive

Biological fluid false positives regularly occur with the use of presumptive testing.
Presumptive testing is the common method used by Australian laboratories and relied upon in the subsequent report.
Caution is advised to avoid any assumption that a presumptive test is conclusive.
Presumptive biological tests are convenient and low cost.
They can yield a false positive to other biological and non-biological matter such as vaginal fluid, faecal matter, blood, rust and bleach.
Interpreting biological fluid test results requires careful consideration by a skilled forensic scientist, to avoid any mis representation before the court.
Error rate

Error Rate

The error rate in biological fluids evidence before the courts, spans two areas, which are interconnected.
Firstly, presumptive testing, is regularly relied upon to confirm biological fluids, when it should more appropriately be confirmatory testing that is relied upon.
Secondly and subsequently, the presumptive positive is relied upon to infer that the biological fluid (apparently identified) is connected to the individual by virtue of the entirely separate DNA likelihood ratio.
The relationship between given biological fluids and the DNA are regularly of critical significance in a matter. and require careful and highly skilled consideration.
Contamination

Contamination

Biological fluid contamination can occur during medical examination, crime scene investigation and within the laboratory.
Appropriate anticontamination protocols should be strictly maintained.
Subtle means of body fluid contamination can occur between locations (transfer) of a particular item of interest. This can be of specific importance when the exacting location of the said body fluid is relevant to the confirmation or refutation of the alleged facts.
Contemporaneous notes from biological fluid examinations along with the DNA results, can adduce further information as to the likelihood and potential implication of contamination.
Testing

Bodyfluid Testing

Presumptive testing of biological fluids such as blood, semen and saliva are commonplace, and known to produce false positives.
Confirmatory testing should be conducted when the type or true existence of body fluid is critical to the facts of an alleged crime.
Accurate testing and interpretation of biological fluids as to the individual and type can contribute substantially to a matter.
The critical importance of body fluids testing is understood, when the erred testing of fluids negates the courts weighting of a robust DNA match within a matter.
Roebuck Forensics can conduct confirmatory testing on suspected biological fluids.
Crime scene

Crime scene examination

DNA and biological fluids are very commonly sampled together and subsequently inferred, and perhaps assumed to be a singular deposition.
Conjunctive evaluation of DNA and biological fluids as sampled, is not in all circumstances scientifically well founded.
DNA is regularly reported with the apparent inference, that it originates from the body fluid sample, when confirmatory testing reveals that no such inference is supportable.
The highly transient nature of both DNA and biological fluids dictates that very careful consideration should be applied to their combined relationship within the crime scene evidence.
Time since event

Time since event

Time since event can be of critical relevance in sexual assault matters, as to the question of semen deposition.
Caution is advised when relying upon subjective testing of fluids.
A common scenario is one where ejaculation is alleged, though semen cannot be scientifically identified with confirmatory testing.
Internally deposited semen rapidly degrades in quantity and structure due to biological and environmental factors, with the likelihood of a true positive fading rapidly in the time since intercourse (TSI).
Deposited fluids can degrade rapidly over time due to environmental factors, with published data being useful in limited scenarios.

Biological Fluids QUESTIONS

What are biological fluids in forensic science?

Biological fluids relevant to forensic science are blood, urine, faeces, vomit, semen, sweat, saliva and bodily secretions.