Blood Spatter Pattern Analysis Ms. Schultz

The Sam Sheppard Case On July 4, 1954 Sam Sheppard called police to report that his wife Marilynn was dead in the bedroom. He said the night before, his wife had gone upstairs to bed while he was asleep on the couch. When he went upstairs, he saw his wife covered in blood. He heard a noise and ran downstairs chasing after a 6’3’’ bushy haired man. The two struggled and Dr. Sheppard was choked unconscious. When police arrived, Marilynn was found with 35 wounds to the head and blood drenched the walls, door, and bed. Her face was almost unrecognizable. Sheppard served 10 years in prison before the US Supreme court rules that the trial had been tainted. The evidence was reexamined. Blood spatters and blood drops provided some of the most compelling evidence. Dr. Paul Kirk, an expert in blood analysis, determined the killer could not have been Sam because the attack was perpetrated by a left handed person. Dr. Sheppard was right handed.

The Sheppard Residence Near Cleveland Marilynn’s Bloody Pillow Steps Leading Down to the Lake Searching for a Murder Weapon

How can the blood left behind tell a story of what happened? Blood Spatter Analysis (BSA) can help determine the type of weapon used as well as a little bit about the nature of the crime including where the victim might have been in relation to the perpetrator.

Blood spatter is: Blood distributed through the air in the form of droplets.

The Bloody Facts Approximately 8% of a person’s total weight is blood. Males have 5-6 quarts of blood. Females have about 4-5 quarts of blood. Once blood has left the body, it behaves according to the laws of physics: Gravity – pulls it down. Viscosity – amount of internal friction in the fluid – it describes the resistance of a liquid to flow. Surface tension – the force that gives the blood the ability to maintain its shape.

Blood Stain Pattern Types Passive – stains created by the force of gravity Drops – acting just with gravity. Drips – blood dripping into blood. Flow – change in shape and direction due to the influence of gravity or movement of the object. Pool – blood that is stationary over time.

Blood Stain Pattern Types Projected – a stain that occurs when some form of energy has been transferred to a blood source. Cast-Off – blood is released or thrown from an object in motion. Arterial spurting – blood exits the body under pressure from a breached artery. Back spatter – blood directed back towards the source of energy. Expiratory blood – blown out of the nose, mouth, or wound as a result of air pressure or air flow.

Blood Stain Pattern Types Transfer/Contact - when an object with blood on it comes in contact with another object that does not have blood on it. Wipe – created when an object moves through an existing stain, removing or altering its appearance. Swipe – transfer of blood from a moving source onto an unstained surface.

Blood Stain Pattern Types Velocity Impact Velocity describes the amount of energy transferred to a blood source in order to create the stains. Velocity is a speed (m/s) with a direction

Velocity Impact Spatter

Can you match the spatter pattern to the cause? Gunshot Baseball Bat Arterial Spurt Gunshot Baseball Bat Arterial Spurt

How to calculate the angle of impact Step 1: Measure the width and length of the blood drop Step 2: Use the equation: Impact angle = arc sin (drop width/drop length)

Videos How to string a crime scene What we can learn from spatter analysis How surface texture affects blood stains