Forensic Serology
Identifying blood and body fluids: presumptive and confirmatory tests, species origin, blood groups, and modern mRNA and microbiome methods.
- 54hours
- 30topics
- 9modules
Foundations of Forensic Serology
What serology means in a forensic context, its place in the laboratory workflow alongside DNA analysis, the composition and properties of blood, and the history of the discipline from the first precipitin tests to immunochromatographic strips.
Start module- Scope and History of Forensic SerologyForensic serology applies the science of body fluids to legal cases, linking a century of blood-group chemistry to today's rapid test kits and DNA workflows.12 min
- Composition and Properties of BloodBlood is a complex tissue of cells, proteins and dissolved molecules, each carrying forensic significance as it ages, dries and reacts to the environment.13 min
- Order of Testing and DNA PreservationThe testing order, from presumptive screening through confirmatory serology to DNA extraction, preserves the evidence needed at each stage.15 min
Presumptive Tests for Blood
The chemical and enzymatic screening tests that indicate the possible presence of blood. Mechanism of action, sensitivity, specificity, common false-positive sources, and the operational context in which each test is deployed.
Start module- Kastle-Meyer TestThe Kastle-Meyer test exploits haemoglobin's peroxidase-like activity to turn phenolphthalein pink, making it the leading presumptive blood test worldwide.12 min
- Leucomalachite Green TestThe leucomalachite green test is a presumptive blood test turning green on oxidation by haemoglobin, a useful complement to Kastle-Meyer.11 min
- Luminol and FluoresceinLuminol glows blue and fluorescein glows yellow-green when they react with trace haemoglobin, letting investigators find bloodstains invisible to the naked eye.13 min
- Bluestar and HemastixBluestar limits DNA damage during latent-blood searches, while Hemastix offers rapid peroxidase-strip screening for blood at the point of care.13 min
Confirmatory Tests for Blood and Species of Origin
Tests that specifically identify human blood by detecting haemoglobin derivatives or unique proteins: crystal methods, immunological confirmatory assays, and the immunological techniques used to determine whether blood is of human or animal origin.
Start module- Teichmann and Takayama Crystal TestsThe Teichmann and Takayama tests confirm blood by growing haematin or haemochromogen crystals from a stain, distinguishing it under the microscope.12 min
- RSID-Blood and ABAcard HemaTraceRSID-Blood and ABAcard HemaTrace are lateral-flow tests that confirm human blood in minutes using anti-human antibodies, unlike classical crystal tests.12 min
- Species of Origin: Precipitin and Ouchterlony TestsPrecipitin and Ouchterlony gel-diffusion tests use antibody-antigen reactions to tell whether crime-scene blood came from a human or an animal.13 min
- Anti-Human Haemoglobin ELISA and Modern ImmunoassaysELISA and related immunoassays detect human haemoglobin with high sensitivity, differing in cross-reactivity from precipitin and lateral-flow tests.13 min
Blood Group Systems in Forensic Context
The ABO, Rh, and MNS antigen systems and the secretor status trait: their biological basis, forensic history and discriminating power, typing methods on stains, and the transition from classical serology to DNA-based individualisation.
Start module- ABO System: Biology and Forensic HistoryKarl Landsteiner's discovery of ABO blood groups gave investigators their first reliable marker for typing crime-scene stains before DNA existed.14 min
- ABO Typing on Stains: Absorption-Elution and InhibitionDried bloodstains can't be ABO-typed by direct agglutination, so serologists use absorption-elution and absorption-inhibition instead.14 min
- Secretor Status and Its Forensic ValueAbout 80% of people secrete ABO antigens into saliva and semen, a FUT2-controlled trait that once multiplied the power of pre-DNA forensic serology.14 min
- Rh, MNS, and Other Blood Group SystemsThe Rh and MNS blood group systems added discrimination to pre-DNA serology, though their antigens degrade fast and DNA has largely replaced them.14 min
Semen Identification
The full toolkit for identifying semen in forensic samples: screening tests, microscopic confirmation of spermatozoa, protein-based assays, and the interpretation of azoospermic or degraded samples.
Start module- Acid Phosphatase Screening for SemenAcid phosphatase from the prostate gland is the oldest reliable screening marker for semen, detectable by colorimetric and fluorescent tests.14 min
- Spermatozoa Identification by MicroscopyMicroscopic examination of spermatozoa after Christmas tree staining remains the definitive way to identify semen, despite the challenge of azoospermic samples.13 min
- p30/PSA and RSID-SemenPSA (p30) and the RSID-Semen strip are the two main protein-based confirmatory tests for semen, each with defined sensitivity limits on vasectomised samples.14 min
Saliva, Urine, and Other Body Fluids
Identification methods for biological fluids other than blood and semen: saliva, urine, sweat, faeces, vaginal fluid, and the forensically important distinction between menstrual blood and peripheral blood.
Start module- Saliva Identification: Amylase and RSID-SalivaSalivary amylase is the primary marker for detecting saliva on forensic exhibits, backed by the RSID-Saliva immunochromatographic assay.12 min
- Urine and Sweat IdentificationUrine and sweat turn up in sexual-assault and drug casework, identified by creatinine, urea and UV fluorescence, though no specific test exists for sweat.12 min
- Vaginal Fluid and Faecal Material IdentificationVaginal fluid and faecal material are identified in sexual-assault casework using glycogen-based tests, ferning and microscopic methods for faecal origin.12 min
- Menstrual Blood versus Peripheral BloodDistinguishing menstrual from peripheral blood matters in sexual-assault cases, using fibrinolytic activity, MMP-10 and D-dimer despite assay limitations.12 min
Modern Body-Fluid Identification: mRNA and Microbiome
Post-DNA advances that use messenger RNA expression profiles and microbial community signatures to identify body fluids with greater specificity and to work on highly degraded or mixed samples where protein-based tests fail.
Start module- mRNA Profiling for Body Fluid IdentificationTissue-specific messenger RNA patterns let analysts identify which body fluid deposited a stain, even after proteins and conventional markers have degraded.13 min
- Microbiome-Based Body Fluid IdentificationEach body fluid carries a distinctive microbial community that metagenomics can read to identify fluid type, even when human protein and mRNA markers fail.13 min
Ageing of Bloodstains
How blood changes over time once deposited, and the scientific methods proposed to estimate how old a bloodstain is, with frank discussion of the current evidentiary limitations.
Start module- Physical and Chemical Changes in Ageing BloodstainsAs a bloodstain ages, haemoglobin oxidises through a colour sequence from red to brown to black, shaped by substrate, humidity, UV light and temperature.13 min
- Spectroscopic Methods for Bloodstain AgeingUV-Vis, near-infrared and Raman spectroscopy track haemoglobin oxidation in ageing bloodstains, though validation gaps keep them research tools for now.13 min
- mRNA and microRNA Approaches to Stain AgeRNA and microRNA markers like miR-let-7b are studied as clues to bloodstain age, but variable degradation rates keep this a research technique, not a standard.15 min
Bloodstain Pattern Introduction, Quality, and Court
A bridge module covering the serological analyst's interface with bloodstain pattern analysis, the quality-assurance framework governing the discipline, and how serology findings are interpreted and communicated in court.
Start module- Introduction to Bloodstain Pattern RecognitionA primer on how serologists and bloodstain pattern analysts divide their roles, and why documenting patterns before any chemical test is non-negotiable.12 min
- Quality Assurance in Serology LaboratoriesHow ISO 17025 accreditation, reagent controls, proficiency testing, and international guidelines keep forensic serology results reliable and legally defensible.12 min
- Serology Evidence in Court: Interpretation and TestimonyHow forensic serologists move from lab findings to courtroom testimony, interpreting probabilistic results and avoiding fallacies that have undermined cases.15 min