Source Attribution
Definition
The inferential step of linking a trace to its donor. Serology identifies blood as human and potentially as a specific genetic type; DNA profiling takes source attribution further by generating a match probability.
- Definition
- Linking a trace to a specific single source and excluding all other sources at an accepted level of confidence.
- Requires
- Individual characteristics sufficient to exclude all other sources at an accepted level of confidence.
- In serology
- Identifies blood as human and determines genetic type. DNA profiling takes this further with match probability.
Common questions
What's the difference between source attribution and just identifying what something is?+
Source attribution goes beyond identifying what the evidence is (like confirming it's blood). It's the step where you link that evidence to a specific, single source and rule out all other possible sources. To do that you need individual characteristics, not just class characteristics.
How does DNA profiling help with source attribution?+
DNA profiling strengthens source attribution by calculating a match probability. While serology can identify blood as human and determine a genetic type, DNA profiling gives you a statistical confidence level that narrows the source down further than serology alone can achieve.
What does it take to say evidence came from one specific person?+
You need individual characteristics that are sufficient to exclude all other sources at an accepted level of confidence. This is a higher bar than just finding class characteristics. The evidentiary standard depends on the type of evidence and the jurisdiction's requirements.
Related terms
- Acquired Characteristics
- Individual characteristics that develop after manufacture through use, wear, damage, or corrosion. A new shoe has only class characteristics; a worn shoe...
- Activity-Level Proposition
- A proposition about what happened. Example: 'The suspect handled the knife' versus 'The suspect never handled the knife.' Activity-level propositions require the...
- Class Characteristics
- Features deliberately or systematically imparted to a group of items by design or manufacture, such as the calibre of a bullet, the...
- Comparison Microscopy
- A technique in which known and questioned samples are viewed simultaneously through split or adjacent fields in a single instrument. Used in...
- Daubert Standard
- The US federal evidentiary standard (Daubert v. Merrell Dow Pharmaceuticals, 1993) requiring that expert testimony be based on scientifically valid methods with...
- Defender's Fallacy
- Dismissing match evidence by citing the large absolute number of people who share the characteristic, ignoring all other evidence that narrows the...
- Elimination Sample
- A known reference sample collected from someone who had legitimate access to a scene or item, used to separate their class and...
- Frye Standard
- The US legal test for admissibility of scientific evidence, originating from Frye v. United States (1923), which required that a technique be...
- Individual Characteristics
- Surface features on a fired bullet or cartridge case that arise from random or unique events (tool wear, corrosion, service damage) and...
- Prosecutor's Fallacy
- The error of treating the RMP (or its reciprocal) as the probability that the defendant is innocent, or as the probability that...
Explained in these topics
- Class versus Individual CharacteristicsThe conclusion that a particular piece of evidence originated from a specific single source. Requires individual characteristics sufficient to exclude all othe...
- Serology Evidence in Court: Interpretation and TestimonyThe inferential step of linking a trace to its donor. Serology identifies blood as human and potentially as a specific genetic type; DNA profiling takes source...