Bloodstain pattern analysis (BPA) at a crime scene shows multiple elliptical blood drops with gamma (tail/satellite) angles pointing toward the doorway. This indicates the direction of blood travel was:

• A From the doorway toward the interior of the room
• B Perpendicular to the direction of the tails
• C From the interior of the room toward the doorway ✓
• D Upward from the floor, indicating a blow-back pattern

Explanation

In blood drop impact analysis, the satellite spatter and elongated tail (gamma) of an elliptical bloodstain point in the direction of travel of the blood drop — i.e., toward the direction the blood was moving when it struck the surface. If tails point toward the doorway, the blood was moving toward the doorway, meaning the source was in the interior (blood traveled from inside toward the door). This allows crime scene reconstruction of movement direction during a bleeding event.

Reference: The Essentials of Forensic Medicine and Toxicology (Narayan Reddy), 34th ed.

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Written and medically reviewed by the StethoPrep medical team.