Bloodstain Pattern Analysis Crime Scene Reconstruction What can

Bloodstain Pattern Analysis

Crime Scene Reconstruction • What can be determined: – Type of injury – Order of wounds – Type of weapon used – Assault & post assault dynamics – Relative force

Crime Scene Reconstruction • Bloodstain pattern analysis should be one of the first forensic investigations conducted. • The probable location of fingerprint, trace, and DNA evidence can be determined from it.

Blood Splash Classification • Six types: – – – Drops Splashes Spurts Pools Smears Trails

Blood Drops • Usually found on horizontal surfaces. If blood drops: – – a short distance, they will be circular. at an angle, they will be elliptical. from several feet up, they appear crenellated. from more than 6 ft. , they will produce side spurts.

Blood Drop • Shape of a drop: – Angle • Both fell 42”, left at a 60 O angle, right at a 10 O angle. The smaller the angle, the more elongated. – Surface texture • Both fell 42”, left hit wall tile, right hit textured wallpaper. – Surface hardness • This drop of blood was tested traveling 4 feet per second onto a hard surface. It was traveling from right to left at a 56 O angle.

Blood Splashes • Occur where blood has flown through the air & hit a surface at an angle. • Usually indicate victim was hit with moving weapon (cast off bloodstain pattern). • Drops appear as exclamation points. • The “dot end” indicates direction of movement.

Blood Spurts • Due to pumping action of the heart. • Usually from large wound to major blood vessel. • Height can indicate the position of the victim (sitting or standing).

Blood Pools • Puddle which can form around the victim. • Quantity of blood can be compared with injuries. • Can indicate where the victim died.

Blood Smear • May be left by victim or assailant. • Often caused by blood on hands or feet and subsequent movement. • Can identify activity after an assault.

Blood Trails • Indicates that the body was moved. – Smeared trail indicates the victim was dragged. – Drops of blood indicate they moved themselves or were carried.

Source of Blood • Blood spatter origin (point of impact) can be determined by finding the point of convergence. 1. Draw straight lines through the long axis of several drops. 2. The point where the lines converge is the spot where the blood came from.