1 Blood has three components that are suspended in plasma.

Erythrocytes are your red cells that transfer oxygen through hemoglobin. It’s what gives blood the red color. Leukocytes, your white cells, are your body’s defenders and support your immune system in fighting infection and disease. Platelets are formed in your bone marrow and play a major role in hemostasis, or plugging up breaches in vessels.

Blood composition is about 55% plasma and 45% formed elements, or cells, which remain suspended due to agitation caused by your circulatory system. That’s called viscosity—it’s density or internal friction. Once blood leaves your body’s

pressurized containment, it’s subject to the forces of gravity and surface tension which dictates its resting shape. That can be in drops, streaks, or pools.

2 Blood Volume

A typical male has between 5 and 6 liters of blood while a typical female has between 4 and 5 liters. This amount of

blood accounts for approximately 8% of a person’s total body weight. When a person loses more than 1 liter of

blood, they are likely to become unconscious. But more than 1.5 liters and death quickly becomes a risk.

The volume of blood on this carpet

indicates that a person has died, even

though there is no body at the scene.

3 The first modern study of blood stains

occurred in 1895.

Blood spatter analysis, more professionally

termed bloodstain pattern analysis (BPA), first

occurred in 1895 when Eduard Piotrowski from

the University of Krakow published a paper

entitled “On the formation, form, direction and

spreading of blood stains resulting from blunt

trauma at the head”. The rather gruesome study

that Piotrowski undertook involved covering one

corner of room with white sheets and studying

the blood patterns that appeared as he beat

rabbits to death.

While gruesome, we still experiment to see

exactly what causes different types of spatter.

These are amazingly accurate when compared to actual crime scenes.

4 Blood spatter analysis can be essential in determining the type of weapon used

during a crime. Comparison A-gunshot, B- expirated blood, C- beating There are many reasons an investigator may

not know what type of weapon was used during a

violent crime. Perhaps a murder was committed

by the weapon was hidden or destroyed along

with the body. Or perhaps a body is so badly

injured that it is impossible to tell how exactly the

murder occurred. The different shapes and sizes

of blood spatter on the surrounding area can

determine the force, weight, and shape of the

weapon. For instance, medium-velocity stains

are generally caused by a blunt object, a fist, or

even a violent spray from a severed artery while

high-velocity spatter that creates tiny droplets is

more likely to be from a gunshot wound.

5 There are ten categories of bloodstain patterns:

1. Single Drop –

These stains are typically from a vertical fall and under low velocity, like when your cut your finger and blood drips to the floor. Blood molecules are very cohesive. They attract and bind in a surface tension that makes a sphere. The drop stays in a ball until it strikes an object or a force acts on it.

Tail

6 There are ten categories of bloodstain patterns:

2. Impact Spatter – These result from forceful impacts between an object and wet blood, causing the blood to break into little droplets. Greater force produces smaller droplets. The study of impact staining provides huge insight into the relative positions of individuals and objects involved in the crime. There are three sub-categories of impacts:

7 There are ten categories of bloodstain patterns:

2. Impact Spatter –

2a. Low Velocity Impact Spatter (LVIS)

Also called Passive Impact Spatters, these are the largest bloodstain drops with a diameter of 4mm or greater. They travel at a slow speed, no greater than 1.5 m/s. They’re associated with being struck by a large, blunt instrument such as a chair or leaking from an open wound. They’re also formed when a large amount of blood has been transferred to another surface and the excess drips down.

8 There are ten categories of bloodstain patterns:

2. Impact Spatter – 2b. Medium Velocity Impact Spatter (MVIS)

These spatters are associated with an intense beating like from a club, a hammer, a gun butt, or a bag of frozen pork chops. (Yes, there was a real homicide case where a guy’s head was caved-in with a bag of frozen pork chops.) MVIS drops are less than 4mm and get propelled at speeds between 1.5 and 7.5 m/s. The further from the target surface that blood is expelled, the larger the drops will be.

9 There are ten categories of bloodstain patterns:

2. Impact Spatter –

2c. High Velocity Impact Spatter (HVIS)

This stain pattern is caused by gunshots, explosions, or contact with high-speed objects like having your throat cut with an electric carving knife. (Had one of those, too.) They’re evident by masses of tiny droplets less than 2mm in diameter and occur at velocities far in excess of 7.5 m/s. There’s no mistaking this type of bloodstain. The angle of impact is evident by an elongated shape – the longer the stain, the longer the angle

from vertical.

10 There are ten categories of bloodstain patterns:

3. Cast-Off Stains – COS are common in scenes such as Billy Ray Hennessey’s axe-murders where straight and

curved lines of blood are made on the walls and ceiling by the centrifugal force of back-

and-forth swings. They produce tear-shaped or oblong stains with ‘tails’ that point in the

direction of travel. By reversing

the line of travel, the path can

be traced or stringed to its area

of convergence.

Beating and Stabbing Spatter = larger individual stains

First blow usually doesn’t result in spatter since there is not yet any exposed blood.

11 There are ten categories of bloodstain patterns:

4. Transfer Bloodstains – These are generally patches and smears of blood deposited secondary to the main, violent event. They say a lot about sequence. It can be when a victim tried to crawl away, the body was dragged, the perpetrator placed a bloody hand on a wall, or when he hid the axe in a closet.

12 There are ten categories of bloodstain patterns:

5. Projected Pattern – This is from arterial damage, such as severed carotids, femorals, radials, and brachials where pressurized blood ejaculates via the still-beating heart. You’ll see groups of big to small splotches, usually in an arc pattern. Very common in stabbings.

13 There are ten categories of bloodstain patterns:

6. Pooling – Usually occurs once the victim is unconscious and passively exsanguinates. That’s the fancy term for bleeding to death. Something telling to a Bloodstain Pattern Analyst is where large pools of blood occur in different locations—no doubt the body’s been moved.

14 There are ten categories of bloodstain

patterns:

7. Blood Trail – These are drops in a line with spines or satellites pointed towards the direction of travel. A running victim will have drops spaced further apart and more elongated than a walking or crawling victim.

15 There are ten categories of bloodstain

patterns:

8. Insect Stains – Not long after death, the bugs show up. They land in the bloodstains and make little tracks all over the place. These are easily confused with HVIS (high velocity impact spatter) to the untrained eye and are known in the industry as Flyspeck.

16 There are ten categories of

bloodstain patterns:

9. Expiration Stains – These are incidental bloodstains associated with injuries to the respiratory and abdominal tracts where a gasping victim expels through the mouth or nose. They appear diluted, more brownish in color due to mixture with saliva or mucous, and look like a fine mist.

17 There are ten categories of bloodstain patterns:

9. Void – Sometimes an item is present during the crime, that was later removed. This could be an object or a body part (because the body fell to the ground or walked away afterward). This outline will give valuable clues about the crime.

18 Examination of a bloody crime scene is a slow and

methodical procedure.

The area is still-photographed from wide, medium, and close-up angles as well as videoed. Each stain pattern is marked, catalogued, and a swab taken for serology or DNA typing. The patterns are then Strung to their Point Of Origin, or area of convergence, and a complex application of trigonometry begins to tell a compelling tale of just what went down.

Point of Origin can be very important. For instance, a

suspect may argue that they acted in self-defense, but the blood spatter analyst determines that the victim was sitting or laying down – hardly on the attack – when the crime was committed.

19

Examining the crime scene

By painstakingly analyzing each

blood drop of this crime scene, it

was determined that there were

actually 3 different sources of

blood. These sources were

matched to wounds on the

victim’s body. Since the drops

overlapped, investigators were

able to determine where the victim

was standing and the actual order

of the wounds.

20 Determining the Point of Origin: Height of Blood Drop

The diameter of a blood drop depends on the height it fell. The

further it falls, the bigger the diameter. It is important to have

reference drops on the surface, as the surface also has a great effect

on the diameter of the drop. For instance, the same blood spattered

on bedsheets, which would absorb blood and therefore distort the

patterns, will look much different than the pattern that would exist on

a pane of glass, which would cause no distortion, or even a concrete

floor, which could lead to ‘satellite’ blood droplets.

Rough Surface

vs Smooth Surface

21

Using Trigonometry to Determine the Point of Origin

22 Examination of a bloody crime scene :

If the drop is elongated, then Spines and Satellites tell the Direction of Travel

In this diagram, both drops are moving in direction 2

23

Examination of a bloody crime scene : The angle of impact helps determine the point of origin

24 Examination of a bloody crime scene : Measuring the Angle of Impact

The angle is measured from the horizontal. The length and width of each drop is measured. Only the body of the drop is measured. Tails, spines, and satellites ignored.

Angle of impact = arcsin (Width/Length)

25

The visual absence of blood can be misleading.

Criminals occasionally clean up a scene or there may be only a small bit of blood emitted. Chemical reactive agents like luminol and phenolphthalein can be applied which visualize latent stains. Light spectrum tools, such as LumiLights, are also used to amplify spots not visible to the naked eye.

Latent blood staining, or attempts to clean up a crime scene, can

also be identified. Latent blood samples are droplets of blood that are not visible to the naked eye. As part of any crime scene investigation the investigator will be looking for latent staining. These stains can be as a result of somebody trying to clean up the area purposely or as a result of accidental contamination. It is vital that once a latent blood sample is suspected samples are taken prior to the forensic testing used to confirm that it is actually blood, the reason being the tests used can interfere with blood typing and DNA preservation.. Latent prints can reveal footprints, fingerprints or detect any objects being moved. Establishing the patterns and directions of any prints can add vital information to the investigation.

26

. It is very difficult to remove all the blood from a crime scene

27 It is very difficult to remove all the blood from a crime scene

(Above) Kitchen floor in normal light. (Right) Kitchen floor treated with Luminol under black light.

28

• Kastle-Meyer test. The Kastle-Meyer test is • a presumptive blood test, first described in 1903, in which the chemical indicator phenolphthalein is used to detect the possible presence of hemoglobin. It relies on the peroxidase-like activity of hemoglobin in blood to catalyze the oxidation of henolphthalin (the colorless reduced form of phenolphthalein) into phenolphthalein, which is visible as a bright pink color

•HemaStix is a strip that has been coated with tetramethylbenzidine (TMB) and will

produce a green or blue-green color with the presence of hemoglobin.

29 Luminol This chemical is used by crime scene investigators to locate traces of blood, even if it has been cleaned or removed. Investigators spray a luminol solution is throughout the area under investigation and look for reactions with the iron present in blood, which causes a blue luminescence. One problem is that other substances also react, such as some metals, paints, cleaning products, and plant materials. Another problem is that the chemical reaction can destroy other evidence in the crime scene.

30 Billy Ray Hennessey

This guy hid in his ex’s attic with an axe for two and a half days, waiting to catch her with another man. Sure enough, she brought one home from the bar. At 3:00 am, Billy Ray crept down from the hatch, snuck into the bedroom, and chopped them to pieces. The crime scene looked like a bomb exploded in a red paint factory.

It took investigators three days to catch Billy Ray. He did the right thing and confessed, then reenacted the murders on video. It was the coldest thing investigators had ever seen. Billy Ray described what he did as if he were watching a movie, going through repeated motions of chopping, back-swinging, and chopping some more. He demonstrated with a 2×2 stick as a prop. (No, they didn’t give him a real axe.) He showed how he modified body positions after death, where he hid his axe in the closet, and where he cleaned himself up. Billy Ray pleaded guilty and received two life

sentences.

During the three days that they hunted for Billy Ray, the Forensic Identification team had sealed the crime scene and independently conducted their Bloodstain Pattern Analysis. Once Billy Ray was done, the detective team compared notes with the forensic team and — unbeknownst to what Billy Ray reenacted — the forensic folks got it exactly right. They’d reconstructed how many blows each victim received, various positions everyone was in, and… who fought back.