IF your EDPuzzle notes are done, you may add/correct them. If not, sit and listen you will need to do them on your own time! T. Trimpe 2006 http://sciencespot.net/ Part A: Watch the Blood Spatter 101 video on EDPuzzle to help you complete this section. 1. What does BPA represent? 2. What are the three types of blood patterns? PASSIVE Bloodstain Pattern Analysis GRAVITY (or drip) stains occurs when pulls blood downward to the floor or surface. They tend to be ROUND and fat without. TAILS TRANSFER stains occurs when a bloody object comes in contact with another object or surface; appears as or stripes PROJECTED SMEARS FORCE Spatter (or ) patterns occur when a is applied to a blood object or pool and are classified as high, medium, or low. VELOCITY The angle of IMPACT is determined by measuring the length and width of each stain. ORIGIN Lasers can be used to determine the point of, or where the source of the blood was located 1
Part B: Watch the BLOOD SPATTER BASICS video on EDPuzzle to help you complete this section. 1. The trainers created scenes to help police officers learn how to investigate crime scenes with blood evidence. 2. The trainers use blood to create their scenes. 3. The height of the drop as well as the speed at which it is traveling affect the and of the blood droplets. 4. True or False? F Blood evidence follows a definite pattern that can be applied to every crime scene. F Popular television shows, such as CSI Miami, are an accurate representation of how investigators analyze real crime scenes. F SIZE MOCK ANIMAL SHAPE Blood evidence is easy to analyze and always tells investigators who is responsible for the crime. 5. The trainer reminds the investigators that what they can't, they can't in a case or court of law. SAY PROVE Glue the lab worksheet on page 65 FAF Right Warning: Some material in this presentation and related videos may be too graphic for some people. Forensic Science Lab Activity T. Trimpe 2006 http://sciencespot.net/ 2
Bloodstain Pattern Analysis Terms Spatter Bloodstains created from the application of force to the area where the blood originated. Origin/Source The place from where the blood spatter came from or originated. Angle of Impact The angle at which a blood droplet strikes a surface. Parent Drop The droplet from which a satellite spatter originates. Satellite Spatters Small drops of blood that break off from the parent spatter when the blood droplet hits a surface. Spines The pointed edges of a stain that radiate out from the spatter; can help determine the direction from which the blood traveled. Satellite Spatter Parent Drop Spines What can an investigator learn from the analysis of a blood spatter? Type of injury/wound(blunt force, sharp force, gunshot, etc.) Weapon type and velocity Number of blows (hits) and which wounds were inflicted first Handedness of assailant (right or left-handed) Position and movements of the victim and assailant during and after the attack Whether death was immediate or delayed and how long ago the crime was committed Source: http://science.howstuffworks.com/bloodstain-pattern-analysis1.htm 3
Blood Spatter Labs This can be messy! Be very careful to keep the blood on the paper and not on yourself, the table, or floor. Hold you hand as steady as possible when making the drops. Brace your wrist against the meter stick to help you. Get a pair of goggles and an apron. Sit quietly until we are ready to continue! If you make a mess or goof up a drop, grab a paper towel and wipe it up immediately! Getting ready 1. Divide the paper into SIX sections. 2. Label one side with 30 S for 30 cm and SINGLE droplet. 3. Label the other side with 60 S for 60 cm and SINGLE droplet. 4. Label the middle with 90 S for 90 cm and SINGLE droplet. 4
#1: How does the HEIGHT of the drop affect the blood spatter? FOR EACH HEIGHT: - Hold the dropper bottle upside down (& away from the ruler) so that the BOTTOM of it is the correct height from the table and blood won t get on the meterstick. - GENTLY squeeze the bottle so that ONE drop of blood is released and lands on your paper. Complete THREE good drops at each height. Repeat the process for the other type of blood! If you make a mess or goof up a drop, grab a paper towel and wipe it up immediately! Compare your BEST drops for diameter and spines and then use your observations to answer the questions on your worksheet. Words to use in your answer: HEIGHT DIAMETER SPINES DONE? Fold up your blood spatter paper and throw away. Put away your goggles and aprons. 5
Compare your BEST drops for diameter and spines and then use your observations to answer the questions on your worksheet. Words to use : HEIGHT DIAMETER SPINES The higher the height of the drop, the WIDER the diameter of the parent drop and the LONGER the spines become. Quick Questions: = round droplets 30 cm 90 cm HEIGHT What is the independent variable in this experiment? DIAMETER/SPINES What is the dependent variable in this experiment? Directions: Lab #2: What happens when MORE THAN ONE DROP HITS the same spot? Divide your paper into 3 sections and label with the heights and an M for multiple drops. You are going to repeat the process from Lab 1, but work as one team NOT TWO and use only PEPTO blood. Be sure to have TWO droplets in the SAME SPOT. 30M 90M 60M Try THREE TIMES from THREE HEIGHTS 30 cm, 60 cm, and 90 cm with the simulated blood (Pepto color) Hold the bottle out away from the meterstick,but brace your hand so it doesn t move between drops.. If you make a mess or goof up a drop, grab a paper towel and clean it up immediately! 6
DONE? Put metersticks and blood on front table Answer the questions for Lab #2 Fold up your blood spatter paper and throw away. Words to use in your answers: HEIGHT DIAMETER SPINES SATELLITES The higher the height of the drop, the WIDER the diameter of the parent drop and the LONGER the spines become. Words to use in your answers: HEIGHT DIAMETER SPINES SATELITES The more droplets that land in the same place, the WIDER the diameter of the spatter pattern and MORE satellites appear that are -shaped OVAL with some with. TAILS TAIL Indicates the direction of movement 7
1 st Law The will BLOOD remain in motion/rest unless acted upon by an unbalanced, FORCE such as causing GRAVITY it to fall or slowing FRICTION it down. The force of the second drop causes the blood to move 2 nd Law The MORE force that is applied, the faster and further the will BLOOD travel. The angle the droplet hits the surface will determine its shape Challenge: How does the ANGLE OF IMPACT affect the blood spatter? Divide a piece of copy paper into three columns and label with the angle for each droplet - 25 o, 45 o, 60 o. Place the paper on the clip board and align the clipboard with the 25 o line. Hold the bottle of blood at a height of 50 centimeters from the top of the paper. GENTLY squeeze the bottle so that a SINGLE drop of blood is released and lands on the paper. Repeat two more times at this angle. Try the test again, but use 45 o and 60 o Done? Write an answer for the question at the top of this slide on the page under your worksheet USING observations from the lab. Draw pictures of the droplets to help you explain what happened. 8
Challenge: How does the ANGLE OF IMPACT affect the blood spatter? The greater the angle with the table (25 o 60 o ), the LONGER the droplet and it has a(n) -shape OVAL with. TAILS The droplets that form from angles close to 90 o with the table tend to be -shaped ROUND without. TAILS Has spines on all sides length depends on the height of the drop NOTE: Add pictures to show the shape at each angle. Quick Questions: ANGLE OF THE CLIPBOARD What is the independent variable in this experiment? SHAPE/LENGTH What is the dependent variable in this experiment? Lab #3: How does the SPEED of an object affect the blood spatter? We are going to walk at different rates (slow, medium, and fast) along a strip of paper and observe the changes in the spatter. Take a pencil with you so you can help label the spatter. Use S for slow, M for medium, and F for fast. Quick Questions: What was the independent variable in this experiment? SPEED 9
Round droplets; close together; spines on all sides, but longer on one side Oval droplets further apart; spines on all sides, but much longer on one side The blood is moving at the same as SPEED the person and continues to move in that direction until acted upon by a FORCE (gravity/friction). The faster the person is moving, the the GREATER distance is between the droplets. The droplets are more -shaped OVAL with longer SPINES on one side. (1) Which of the three blood droplets shown would have been created by a wound in the lower part of the leg? Explain. (2) If you have a blood droplet like this one, what does it tell you? Explain. (3) How does Newton s First Law of Motion apply to this droplet? (4) If you have a blood droplet like this large one, what does it tell you? Explain. (5) If you find a trail of blood with droplets that are round and close together with small spines, what could this mean? 10