Projected Pattern
Definition
A pattern produced when blood is expelled under pressure or force exceeding gravity, as in arterial spurting, impact spatter, or cast-off from a swinging weapon.
- Field
- Bloodstain pattern analysis
- Cause
- Force exceeding gravity
- Examples
- Arterial spurting, impact spatter, cast-off
- Contrast
- Passive gravity-driven staining
Common questions
How does a projected pattern differ from a passive bloodstain?+
A passive pattern such as a drip or pool forms purely under gravity with no external force applied, while a projected pattern requires an additional energy source, an arterial pulse, a blunt or sharp impact, or a swinging weapon flinging blood off its surface, a distinction central to reconstructing what happened at a scene.
Can arterial spurting and impact spatter be told apart within a projected pattern?+
Yes, arterial spurting typically produces a rhythmic, undulating pattern reflecting the heartbeat with characteristic gaps, while impact spatter produces a more uniform radiating pattern of smaller droplets from a single forceful strike, so their shapes and distributions are analysed separately.
Related terms
- Bloodstain Pattern Analysis (BPA)
- The scientific discipline that examines the size, shape, distribution, and location of bloodstains to reconstruct the events that produced them, addressing questions...
- IABPA
- The International Association of Bloodstain Pattern Analysts, founded 1983, which sets training standards and accreditation criteria for BPA specialists.
- Passive Drip
- A stain formed when blood falls from a source under gravity alone. The resulting drop is roughly circular; its diameter correlates with...
- Presumptive Test
- A fast, low-cost, class-specific screen used to triage a caseload before instrumental work begins. Examples are Marquis reagent for opioids and amphetamines,...
- Transfer Stain
- A stain deposited when a wet, blood-bearing object contacts a surface and leaves an impression. Shoe soles, hands, fabric, and tools can...