CSI - bloodstain pattern
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Created by:
clairerimkus on December 13, 2010
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34 terms
Terms | Definitions |
|---|---|
 Blood spatter | A random distribution of bloodstains that vary in size and may be produced by a variety of mechanisms |
| As blood drop falls, velocity increases until terminal velocity reached | ~25 feet/sec, for ~20 to 25 feet |
| the greater the volume of blood drop, | the larger the diameter of the resulting bloodstain |
| The greater the height from which the blood drop falls (up to ~7 feet) | the larger the diameter of the resulting bloodstain |
| Blood falling through the air takes the shape of | a sphere |
| satellite stains | As blood strikes a surface, smaller droplets may break off and land near the parent stain |
| to produce "spatter" | surface tension must be overcome |
| surface tension | Force that pulls the molecules of a liquid toward its interior (decreases surface area, resists penetration) |
| Arterial Gushing and Spurts | blood under pressure from any breach in an artery |
| Expirated Blood | blood forcefully expelled from the nose/mouth to clear airway |
| Cast-off Stains | blood flung or projected from an object in motion or suddenly stopped |
| Drip Patterns | pattern caused when liquid blood drips into another liquid |
| Shadowing/Ghosting/Void | area within a generally continuous bloodstain that lacks blood |
| Skeletonized | bloodstain that although disturbed still reflects its original shape and size |
| Pattern Transfer | stain created when wet bloody object comes in contact with another surface |
| Swipe | transfer of blood onto a target by a moving object that is bloodstained |
| Wipe | stain created when an object moves through a preexisting bloodstain on another surface |
| Pooling | large volume, absence of satellite stains. |
| Passive Drops | Only force acting on blood is gravity (low velocity). Type of surface affects the blood drop |
| "Medium Velocity" Spatter Force and Energy | between 5 to 25 ft/sec |
| "Medium Velocity" Spatter Stain size | between 1 to 4 mm in diameter |
| "Medium Velocity" Spatter produced by | beatings, castoff, some gunshots |
| "High Velocity" Spatter Force and Energy | 100 ft/sec or above |
| "High Velocity" Spatter Stain Size | 1 mm or lower in diameter, May see "misting." Mostly associated with gunshots or expirated blood |
| Swipe or Wipe? | sometimes hard to tell so just call it "altered stain" |
| Satellite drops tend to be | round, raised |
| Directionality | The pointed end of an elongated stain points to the direction of travel. Satellite drops/spines show the directionality of the drop. |
| Area of Convergence | 2D. Relative location of the source of blood that has created the pattern. Determined by drawing straight lines through the elongated axes |
| How do you choose for individual spatter selection? | Stains with good geometry, Random selection (representative), No set number |
| Area (Point) of Origin | The location of the blood source creating the pattern in a three-dimensional perspective. Must determine angle of impact |
| Angle of Impact | The angle at which the blood drop strikes the surface of a target |
| Mathematical relationship between width and length of an elliptical bloodstain | i = sin-1 W/L.The arc sin (sin -1) of the bloodstain width divided by bloodstain length |
| Why do we care about angle of impact? | Assist in determining manner of death, Reconstruction of events, Corroborate/disprove a story, May lead to discovery of additional evidence, Determine which stains for DNA testing |
| Documentation | Overall/mid-range photos, Exam quality photos, Directional cues, Measurements |
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