CHE 107 Lecture Notes - Lecture 27: Blood Residue

• School: Pace University
• Department: Chemistry
• Course: CHE 107
• Professor: Richardson

Document Summary

Direction of travel of blood striking an object may be discerned b/c pointed end of a bloodstain always faces its direction of travel. Impact angle of blood on a flat surface can be determined by measuring degree of circular distortion: at right angles, blood drop is circular, as angle decreases, stain becomes elongated. Mathematically, angle of impact can be calculated by equation & determining inverse of sine a: Length of blood stain: bloodstain spatter patterns: Can"t illuminate specific events that produced spatter pattern: low velocity spatter: Drops w/ diameters of 4 mm or more normally produced by applied force of up to 5 ft. /sec: medium velocity spatter: Drops w/ diameters from 1-4 mm w/ applied force of 5-25 ft. /sec: high velocity spatter: Drops w/ diameters of less than 1 mm from an applied force of. Classifications of low, medium, & high velocity can"t illuminate specific events that produced stain size pattern. One should use stain size categories very cautiously.