Spot the Differences View Tube Daily CSI

Spot the Differences View Tube Daily CSI
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Answers: Straw, popcorn, tie, cord, patch and pear.
Find the 6 differences between the two pictures. Answers: Straw, popcorn, tie, cord, patch and pear.

Daily CSI Spot the Differences An Apple A Day

Find the 6 differences between the two pictures.
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Answers: Apple, branch, tree root, beaver’s ear, wood chips, snake
The answers are … Answers: Apple, branch, tree root, beaver’s ear, wood chips, snake Source:

Kendall/Hunt Publishing Company

Blood at the Crime Scene

Blood at the Scene of the Crime
Investigators often find blood at the scenes of violent crimes. They can use the location, distribution, and pattern of blood and bloodstains to help reconstruct the crime. Kendall/Hunt Publishing Company

Trying to clean up every trace of blood after a violent crime can be next to impossible – especially if there was a great deal of blood. Often criminals will think that they have sufficiently cleaned up a room, but end up missing minute amounts of blood spatter. Kendall/Hunt Publishing Company

Dried Blood Dried blood will appear a deep burgundy or brownish black in color. If an investigator does find a suspicious stain – no matter how small – a photograph is taken followed by a chemical test which is performed to confirm that it is indeed blood and not something else. Kendall/Hunt Publishing Company

Forensic experts are aware of this and as a result one of the first things they will often do at a crime scene is to simply bring in a powerful light. This powerful light then can be used by investigators to find any small traces of dried blood that may be left at a crime scene. Kendall/Hunt Publishing Company

Unknown Stain at a Scene
Questions to be answered: Is it blood? Is it human blood? Whose is it? (What type of blood is it) Determine blood type, alcohol content, drugs present Determine the method(s) in which blood may have been deposited Kendall/Hunt Publishing Company

Is it Blood? The first question is an obvious one. A rust stain can look very much like a dried bloodstain, so some sort of screening test should be applied. Kendall/Hunt Publishing Company

Blood contains an enzyme called peroxidase that makes its identification easier. The ‘heme’ in hemoglobin catalytically decomposes perioxides with the production of oxygen. Many chemicals react with peroxidases to give a visible color change indicating that the stain is blood. Kendall/Hunt Publishing Company

Presumptive Tests Used to determine if a stain is blood.
Benzidine Test – presence of perioxidase makes the chemical turn blue Kastle-Meyer color test—a mixture of phenolphthalein and hydrogen peroxide; the hemoglobin will cause the formation of a deep pink color if blood is present Hematest® tablet—reacts with the heme group in blood causing a blue-green color Luminol test—reaction with blood to produce light Takayama test – blood heated on a hot stage microscope and Takayama reagent added. Kendall/Hunt Publishing Company

Benzidine Test For many years, this was the most common color test. However, benzidine has been identified as a known carcinogen, and its use has been generally discontinued. Presence of peroxidase makes the chemical turn blue. Kendall/Hunt Publishing Company

The Kastle-Meyer Test Replaced the Benzidine Test Phenolphthalein reagent/hydrogen peroxide combination are used. When reduced phenolpthalein reagent and hydrogen perioxide contact a blood stain, the presence of peroxidase makes the chemical turn a deep pink color. Kendall/Hunt Publishing Company

Hematest Tablet Test tablet—reacts with the heme group in blood causing a blue-green color Kendall/Hunt Publishing Company

Hematest or Hemastix Field investigators have found Hemastix to be a useful presumptive field test. Designed as a urine dipstick test for blood, the strip can be moistened with distilled water and placed in contact with a suspect bloodstain. Hematest® tablet—reacts with the heme group in blood causing a blue-green color Kendall/Hunt Publishing Company

Luminol Luminol test—reaction with blood to produce light Kendall/Hunt Publishing Company

Luminol A more sensitive chemical test used nowadays involves luminol. It has the added advantage that it glows in the dark. Comes in aerosol cans and can be sprayed over the crime scene. Kendall/Hunt Publishing Company

Luminol At a crime scene, large pools of blood are easy for forensic investigators to spot. But what if all the blood has been cleaned up by the assailant? Blood that has been cleaned away can be detected using a powerful chemical compound called luminol. Kendall/Hunt Publishing Company

Luminol reacts with a portion of the hemoglobin in red blood cells called “heme”. When luminol comes into contact with “heme” it reacts and produces a byproduct – a greenish-blue light or glow. Kendall/Hunt Publishing Company

Chemiluminescence When blood samples are sprayed with activated blood detection solution, a blue glow appears. This glow is seen due to a phenomenon known as chemiluminescence. Kendall/Hunt Publishing Company

Chemiluminescence Is the emission of light as a result of a chemical reaction. When in contact with the activated luminescent detection solution, the blood sample acts as a catalyst for the chemiluminescent reaction. Kendall/Hunt Publishing Company

The ions in the solution become activated to an excited state. As the ions relax back to their ground state, a photon in the visible region of the spectrum (1425 nm) is released. The emitted photons are seen as a glowing blue light. Kendall/Hunt Publishing Company

Luminol When the lights are turned off, even minute traces of blood glow. The luminol test is the most sensitive of the three tests. It can detect blood dilutions of 1:5,000,000. Kendall/Hunt Publishing Company

The luminol test is a very sensitive indicator for dried and even washed blood. False positives can be caused by certain medals, (Cu, Fe, Co), bleach, and sometimes even plaster walls. This is a presumptive test because it can give false positives. Kendall/Hunt Publishing Company

There are several reasons why luminol is used.
It is nondestructive, meaning that after spraying, officers can still perform other tests to confirm that it is in fact, blood. Kendall/Hunt Publishing Company

Another reason is that luminol works better after a long period of time after the blood has aged and decomposed. As the red blood cell ages and decomposes, it exterior cell membrane breaks down and exposes the hemoglobin. Thus the exposed hemoglobin can more easily come into contact with luminol. Kendall/Hunt Publishing Company

In fact, if it is suspected that blood has just been cleaned off a surface, investigators will spray the area with hydrochloric acid (causing the red blood cell membranes to break down) before applying luminol. Kendall/Hunt Publishing Company

Another advantage to luminol
is that it can paint the way to further evidence or how events may have unfolded. For example, if luminol sprayed on a carpet produces a glow, officers might peel back the rug to reveal floorboards still soaked with blood. Kendall/Hunt Publishing Company

Or perhaps the glow will disclose the direction in which a criminal walked or dragged a body, or whether the victim was shot from behind or above.

Some disadvantages to luminol include
the fact that it cannot distinguish between human blood and animal blood, since both contain hemoglobin. Luminol can also react in the presence of similar substances such as metals like copper, nickel paints containing metals, rust, cleaning produces like highly concentrated bleach, iodine and even weird things like horseradish, watermelon and some citrus fruits. Kendall/Hunt Publishing Company

However, Lumiol’s reaction to each of these differs in intensity – Metals cause an immediate glow that quickly fades, while blood glows longer. A forensic expert can tell the difference, and then perform more conclusive tests to determine whether the blood is in fact of human origin. Kendall/Hunt Publishing Company

False Positive – a test that comes out positive when may not be positive for the substance. Unfortunately there are several substances that give a false positive This test is a presumptive test because it can give false positives. Potatoes Horseradish Radishes Lemons Oranges grapefruit Kendall/Hunt Publishing Company

Takayama Crystal for Blood
– blood is heated on a hot stage microscope and Takayama reagent added. A crystal is formed. Kendall/Hunt Publishing Company

So. . . Anyone thinking that cleaning up after a bloody crime scene will erase evidence of their crime is mistaken – blood is one stain that cannot be “shouted out”. Kendall/Hunt Publishing Company

Is it human or is it animal blood?
After there is a confirmation for the presence of blood. . . The next question is: Is it human or is it animal blood? Kendall/Hunt Publishing Company

Is it Human or Animal? Once a spot has been confirmed as blood, the next question is whether it is human blood. The suspect may claim that the blood stain on his shirt came from a very rare steak he had been carving the night before. Kendall/Hunt Publishing Company

1. Microscopic Examination of human blood.
Human Blood - Red blood cells are most numerous; 5 to 6 million per mm3 White blood cells are larger and less numerous; 5 to 10,000 per mm3 Platelets are tiny, cellular fragments; 350 to 500,000 per mm3 Kendall/Hunt Publishing Company

Sickle Cell Kendall/Hunt Publishing Company

Animal Blood Microscopic examination Larger nucleic red blood cells Frog Blood Kendall/Hunt Publishing Company

2. The Precipitin Test Precipitin test—blood is injected into a rabbit; antibodies are formed; the rabbit’s blood is extracted as an antiserum; the antiserum is placed on sample blood. The sample will react with human proteins, if human blood is present. This test is very sensitive and requires only a small amount of blood. Kendall/Hunt Publishing Company

Precipitin Test The standard test to determine if a blood stain is human is called the precipitin test. Human blood cells are injected into a lab animal and the animal’s immune system creates antibodies that specifically bind to human blood cells. Kendall/Hunt Publishing Company

These anti-human blood antibodies can be collected from the animals and used to test for the presence of human blood. Kendall/Hunt Publishing Company

There are many ways to carry out the precipitin test.
It can be performed using a simple test tube. A small volume of anti-human blood antibody solution is first introduced into the test tube. Next, a solution of suspected human blood is added to the top. Kendall/Hunt Publishing Company

The formation of a dark ring at the interface indicates the blood is human.

Precipitin Test Kendall/Hunt Publishing Company

Use of an agar gel plate . . . The precipitin test can also be done using an agar gel plate. The anti-human antibody is put in one well, and the suspected blood solution is put in another. The antigens and antibodies fuse toward one another, and the formation of a dark line between the two wells indicates the blood is human. Kendall/Hunt Publishing Company

The Precipitin Test Kendall/Hunt Publishing Company

The reaction can be intensified by applying a voltage to the plate. Once the blood has been shown to be human, the Lattes method can be used to determine the blood type. Kendall/Hunt Publishing Company

End of Blood Detection

Bloodspatter

Blood Spatter Evidence
A field of forensic investigation which deals with the physical properties of blood and and the patterns produced under different conditions as a result of various forces being applied to the blood. Blood, as a fluid, follows the laws of physics. Kendall/Hunt Publishing Company

Blood Evidence Class evidence for blood would include blood type. If you can determine the DNA you would have individual evidence. Blood stain patterns are considered circumstantial evidence in a court room. Experts could argue many points including direction of travel, height of the perpetrator, position of the victim, left/right hand, whether the body was moved, etc. Kendall/Hunt Publishing Company

Blood Pattern Reconstruction
Scene Pattern Reconstruction 1. Stain condition 2. Pattern 3. Distribution 4. Location 5. Directionality —From “Cracking Cases” by Dr. Henry C. Lee Kendall/Hunt Publishing Company

The patterns left by falling, projected, or smeared blood can help the forensic investigator interpret and reconstruct what has happened at a crime scene.

Bloodspatter patterns are often used to prove or disprove the suspect’s account of what happened.

Careful observation of the position and shape of stain patterns can give information such as the: direction of travel the angle of impact The position of origin The blood droplet’s speed at the time of impact. Kendall/Hunt Publishing Company

History

Dr. Eduard Piotrowski 1894 wrote the earliest reference the bloodstain pattern analysis Kendall/Hunt Publishing Company

Dr. Victor Balthazard 1939 First to use physical interpretation of stains. Kendall/Hunt Publishing Company

Dr. Paul Kirk 1955 Recognized the value of bloodstain interpretation in crime scene reconstruction. Was the defense witness in Dr. Sam Sheppard’s trial. Kendall/Hunt Publishing Company

Professor Herbert Leon MacDonell
1971 Promoted bloodstain pattern interpretation as a tool in modern criminalistic labs. Published an in depth study of bloodstain patterns. Has important implications for any investigator who seeks to trace the direction, dropping distance, and angle of impact of a bloodstain. Kendall/Hunt Publishing Company

The International Association of Bloodstain Pattern Analysis
1983 First association for criminalists specializing in bloodstain patterns. Kendall/Hunt Publishing Company

Blood Droplet Characteristics
A blood droplet will remain spherical in space until it collides with a surface Once a blood droplet impacts a surface, a bloodstain is formed. Kendall/Hunt Publishing Company

1. Surface texture is important in the interpretation of a bloodstain.
Surface tension pulls blood into a sphere until something disrupts it. In general, the harder and less porous the surface, the less spatter results. Kendall/Hunt Publishing Company

Surface Texture Affects bloodspatter shape
The softer and more porous the surface, the more a blood drop will break apart. The harder and less porous the surface, the less the blood drop will break apart. Kendall/Hunt Publishing Company

A droplet falling from the same height, hitting the same surface at the same angle, will produce a stain with the same basic shape. How will the shape change as the height is increased or decreased? Kendall/Hunt Publishing Company

Conditions Affecting Shape of Blood Droplet
Size of the droplet Angle of impact Velocity at which the blood droplet left its origin Height Texture of the target surface On clean glass or plastic—droplet will have smooth outside edges On a rough surface—will produce scalloping on the edges Kendall/Hunt Publishing Company

2. The direction of travel of blood striking an object may be discerned by the stain’s shape. The pointed end of a bloodstain always faces its direction of travel. Kendall/Hunt Publishing Company

Directionality is usually obvious as the pointed end of the bloodstain (tail) will always point in the direction of travel. Kendall/Hunt Publishing Company

Impact The more acute the angle of impact, the more elongated the stain. 90 degree angles are perfectly round drops with 80 degree angles taking on a more elliptical shape. At about 30 degrees the stain will begin to produce a tail. The more acute the angle, the easier it is to determine the direction of travel. Kendall/Hunt Publishing Company

Angle of Impact “The tail tells the tale”
90 degrees – 60 degrees – 30 degrees – 10 degrees – Kendall/Hunt Publishing Company

Calculating Angle of Impact
Kendall/Hunt Publishing Company

By accurately measuring the length and width of a bloodstain, the impact angle can be calculated using the SIN formula below SIN < = Width (a) 1.5cm Length (c) 3.0cm Width (a) 1.5cm = SIN < 0.5 = SIN < < = 30 degrees Kendall/Hunt Publishing Company

Area of Intersection and Convergence
The location of the blood source can be determined by drawing lines from the various blood droplets to the point where they intersect. The area of convergence is the point of origin; the spot where the “blow” occurred. It may be established at the scene with measurement of angles by use of strings. Kendall/Hunt Publishing Company

String Convergence in a 2 Dimensional Plane Convergence Kendall/Hunt Publishing Company

Spatter size is dependent on velocity or speed

Low Velocity – Large stains
Gravitational pull up to 5 feet/sec. Relatively large stains 4mm in size and greater Kendall/Hunt Publishing Company

Medium Velocity – medium
Force of 5 to 25 feet/sec. Preponderant stain size 1 to 4mm in size Kendall/Hunt Publishing Company

High Velocity – misting stains
Force of 100 feet/sec. and greater Preponderant stain size 1mm in size and smaller Mist like appearance Kendall/Hunt Publishing Company

Categories of Bloodstains
Passive Transfer Projected

Categories of Bloodstains
1. passive 2. transfer 3. projected Kendall/Hunt Publishing Company

Passive Kendall/Hunt Publishing Company

Transfer Kendall/Hunt Publishing Company

Swipe – putting blood onto a surface Wipe – removing blood from an existing stain. Kendall/Hunt Publishing Company

1. Angular drops 2. high velocity 3. hair impact 4. hair swipe 5. fabric swipe Kendall/Hunt Publishing Company

Projected Kendall/Hunt Publishing Company

Cast Off Patterns Blood cast from a moving object Occurs with the backstroke during repeated blows or stabs Not true spatter Spatter averages 6mm in diameter Blunt or stab wounds (# of trails + 1 = # of blows. Axe or machete (# of trails = # of blows) Kendall/Hunt Publishing Company

Cast-off Bloodstains 7 blows As the angle decreases, elongation increases Kendall/Hunt Publishing Company

Arterial Gushing Is S shaped Can be several feet away and produce Kendall/Hunt Publishing Company

Void Pattern Produced when an object located between the source of the blood and the surface being spattered is removed. It is a negative image of the object. Kendall/Hunt Publishing Company

Void pattern – negative image

Skeletonization of Bloodstains
Partially dry stains have a ring that outlines the original spatter. Kendall/Hunt Publishing Company

Drying Time Drying begins at the periphery and proceeds inward. Drying time is affected by Surface type Amount of blood present Climatic conditions Kendall/Hunt Publishing Company

Clotting Time Clotting time outside of the body ranges from 3-15 minutes. Spattered clots indicate that time passed between initial bleeding and later blows. Kendall/Hunt Publishing Company

Example – beat/hit – break – beat/hit Chunks will now be ejected when hit. Coughing of clotted blood may indicate post injury survival time of the victim. Kendall/Hunt Publishing Company

Packaging When packaging and storing blood evidence, do not block out air – a sealed container may trap any moisture present and cause mold and mildew to form. Always air dry. Paper bags or envelopes may be used. Kendall/Hunt Publishing Company

training_intro.html A Killers Trial/Nova - Library Dr. Sam Sheppard Kendall/Hunt Publishing Company

Bloodstain Terminology
Angle of impact—angle at which blood strikes a target surface. Bloodstain transfer—when a bloody object comes into contact with a surface and leaves a patterned blood image on the surface Backspatter—blood that is directed back toward the source of energy Cast-off—blood that is thrown from an object in motion Kendall/Hunt Publishing Company

Contact stain—bloodstains caused by contact between a wet blood-bearing surface and a second surface which may or may not have blood on it Transfer—an image is recognizable and may be identifiable with a particular object Swipe—wet blood is transferred to a surface which did not have blood on it Wipe—a non-blood bearing object moves through a wet bloodstain, altering the appearance of the original stain Kendall/Hunt Publishing Company

Directionality—relates to the direction a drop of blood traveled in space from its point of origin Terminal velocity—the greatest speed to which a free falling drop of blood can accelerate in air. It is dependent upon the acceleration of gravity and the friction of the air against the blood—approximately 25.1 feet/second. High velocity—greater than 25 feet per second, usually 100 feet per second; gives a fine mist appearance Medium velocity—5 to 25 feet per second Low velocity—5 feet per second or less Kendall/Hunt Publishing Company

More about Serology For additional information about blood evidence, and famous crimes that involves serology, check out Court TV’s Crime Library at: Kendall/Hunt Publishing Company

People of Historical Significance
Paul Kirk ( ) was a professor of criminalistics and biochemistry at Berkeley in California. He actively assisted law enforcement organizations from 1935 to His book, Crime Investigations, contained a chapter in which he discussed the application of blood stain pattern analysis to criminal investigations. Dr. Kirk analyzed the blood stain pattern photos from the Sam Sheppard case and was instrumental in Sheppard’s release at his second trial. Find out more about the case at Courttv’s crime library. Kendall/Hunt Publishing Company

People in the News Herbert L. MacDonell is considered by many as the father of modern bloodstain pattern analysis. He is the director of the Lab of Forensic Science and founder of the Bloodstain Evidence Institute (1973) in Corning, NY. His work, Bloodstain Pattern Interpretation, helped to jump start this discipline. He has consulted on criminal cases in all 50 states, in addition to testifying in the O.J. Simpson trial and in the assassination cases of Sen. Robert F. Kennedy and Dr. Martin Luther King Jr. Kendall/Hunt Publishing Company

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