Teacher Notes

Blood Stains at the Crime Scene

Super Value Laboratory Kit

Materials Included In Kit

Simulated antibody A, 500 mL
Simulated antibody B, 500 mL
Simulated blood, type A, 500 mL
Simulated blood, type AB, 50 mL
Simulated blood, type B, 500 mL
Simulated blood, type O, 600 mL
Microcentrifuge tubes, 450
Pipets, Beral-type, 450
Spot plates, 15

Additional Materials Required

(for each lab group)
Water, distilled
Simulated blood-soaked items from mock crime scene
Scissors (optional)

Prelab Preparation

Blood samples for Part I tests can be dispensed and labeled prior to class use. Student assistants can dispense the simulated blood and antibodies into labeled microcentrifuge tubes for each lab group. One mL per tube is more than enough for the basic tests.

Prepare unknowns for testing in Part II of the lab to fit your crime scene teaching unit and strategy. Two scenarios are described on the next page for possible stand-alone use. Use one of them or incorporate blood testing into a larger crime scene scenario of your own design.

Safety Precautions

Some of the simulated blood contains alcohol and is flammable. Do not use near open flame. Wear chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron. Please consult current Safety Data Sheets for additional safety, handling and disposal information.


Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. Liquid materials can be disposed of according to Flinn Suggested Disposal Method #26b.

Teacher Tips

  • Enough materials are provided in this Super Value Kit for 5 classes of 30 students each, working in pairs (75 total student groups). All plastic spot plates are completely reusable. Part I can be completed in 30 minutes. Part II will vary with your teaching strategy.
  • The theory of blood chemistry and blood type genetics as outlined in the Background should be studied and discussed prior to doing this lab activity.
  • This lab does not use any real blood components and therefore, poses no greater risk than the handling of small quantities of chemicals involved in the tests.
  • The simulated blood solutions in the kit can be used to soak items in your own mock crime scene. Simply soak the items in the simulated blood solutions and let them dry. Soak the items in a small amount of distilled water (several mL) to get the “blood” out of the item for blood typing tests. Make the crime scene blood match the desired results of your mock crime scene.
  • Paternity Scenario

    Provide blood samples as follows:

    Child: Type O
    Mother: Type O
    Potential Father 1: O
    Potential Father 2: A
    Potential Father 3: AB

    Have students conduct blood typing tests and then determine which, if any, potential fathers can be eliminated (only PF3 in this scenario). Many other combinations can be created.

  • Robbery Mystery

    The police were called at 10:00 p.m. to the residence of one Rupert and Rupina Clodhopper. They had returned from a tea-sampling affair that evening to find their back patio door had been broken into.

    When police arrived, they questioned the Clodhoppers and found that they had a wall safe installed one year ago to store approximately $10,000 in jewelry.

    The Clodhoppers were asked who knew about the safe and jewelry and they stated that they have had only six house staff employees in the last year: Mike, Bob, Chris, Mary, Susan and Jessica.

    The police evidence technician team arrived and collected and tagged bloodied broken glass and one cotton glove.

    The patio door was actually twin French doors with eight windows each arranged in a 2 by 4 column fashion (see Figure 4).

  • The broken pane of glass is indicated by shading.

    Each of the employees was asked for and agreed to give a sample of blood for study. The police questioned each suspect and their answers are listed here.


    Provide a small piece of soaked cotton cloth (piece of glove) and blood samples for each suspect. Have students conduct blood typing tests and then defend their suspicions about the crime scene.

    The crime scene indicates a right-handed burglar due to the broken glass being on the right door. This helps Bob and Susan’s defense. The blood type (you pick the guilty party by the blood type soaked on the cotton cloth) will identify the burglar or eliminate some depending upon your blood type choices. Make a diagram for your crime scene with students like the following to get a systematic look at the evidence.


Answers to Questions

Part 1. Blood Typing Tests

  1. What do the results for blood type AB indicate about the types of proteins on the red blood cells?

    Since the blood reacted with both antibodies, it indicates that the blood cells contain both the A and B proteins.

  2. What proteins are indicated on the red blood cells in the type O results?

    Since there was no reaction with either antibody, it would indicate that neither protein A nor B were present.

  3. Which blood type would be considered the “universal recipient” (a person who can receive all blood types)? Explain why the person can receive all blood types.

    Type AB would be considered a “universal recipient” since it lacks both A and B antibodies. See Background information for further clarification.

Part 2. Crime Scene Blood Testing Results

Will vary depending upon crime scene scenario.


Special thanks to Gary Schiltz, Glenbard West High School, Glen Ellyn, IL, for providing this kit idea.

Student Pages

Blood Stains at the Crime Scene


Blood stains at a crime scene can be crucial in solving the crime. Numerous analytical techniques can be used to study blood stains. Often the blood type can be determined and potentially matched to suspects associated with the crime. Learn the principles of blood typing with simulated blood-typing materials.


  • Dominant vs. recessive alleles
  • ABO Blood Typing System
  • Phenotype
  • Genotype



Early attempts to transfer blood from one person to another produced varied results. Sometimes it seemed to help the recipient and other times it produced very serious consequences. Eventually, it was discovered that each individual has a unique combination of substances in his or her blood. Some of these substances may be compatible with another person’s blood and some may not be compatible. These findings led to the discovery and development of procedures to type an individuals’ blood. It is now known that safe transfusions of blood depend upon properly matching the blood types of the donors and the recipients.

Genetics of Blood Types

ABO blood type is determined by the presence or absence of specific proteins on an individual’s red blood cells. A basic genetic principle is that an individual’s inherited genes determine which proteins are produced in the individual’s body. In the ABO blood typing system (just one of many blood factors) the blood proteins (antigens) are called the A and B proteins. The presence or absence of the A and B proteins on the red blood cells determines the individual’s blood type in the ABO typing system. Individuals whose red blood cells contain protein A and lack protein B have type A blood. Those with protein B and lack protein A are called type B. Individuals with both protein A and protein B are called type AB and individuals with neither of the proteins is called type O.

ABO blood type is a genetic example of multiple alleles. There are three alleles in the gene pool for ABO blood type (i.e., IA, IB, i). IA codes for protein A, IB codes for protein B and i codes for neither protein A nor protein B. Within this multiple allele pool the gene interactions illustrate both simple dominance as well as codominance. (Remember each individual has only two alleles for each trait even if there are multiple alleles in the gene pool.) When the IAi allele combination occurs, the individual is blood type A. When the IAIB combination occurs, the IA and IB alleles are codominant and the individual is blood type AB. The chart below illustrates the allele combinations, resulting blood type, proteins on the red blood cells and antibodies in the blood for the four blood types in the ABO system.

Blood Transfusions

Blood groups are critically important with respect to transfusions. If someone with type A is given a transfusion of type B blood, the two bloods will interact, clump and clog arteries which will have serious consequences to the individual. The clumping reaction is caused by the interaction of the proteins on the red blood cells and the antibodies present in the blood plasma. Antibodies are produced by the body in reaction to foreign proteins and are important in protecting the body against disease. Antibodies cannot distinguish a disease protein from protein on red blood cells. Individuals do not produce antibodies for proteins of their own red blood cells, but do produce antibodies for foreign proteins. Thus, a person with type A blood (A protein on surface of red blood cells) does not produce a antibodies. This person does produce b antibodies. If given the transfusion of type B blood, the antigens and antibodies of the mismatched blood will react and clump (a natural defense mechanism for foreign proteins). The illustrations below, in a very oversimplified way, illustrate the makeup of each of the four blood types.
Using the same illustration scheme, a transfusion of type B blood into an individual with type A blood might be illustrated as follows:
Similarly, a person with type B blood must not be given a transfusion with type A blood.

Because type AB blood lacks both a and b antibodies, it would appear that an AB person could receive a transfusion of blood from any other type. For this reason, type AB persons are sometimes call universal recipients. It should be noted, however, that type A (b), type B (a) and type O (a and b) blood still contain antibodies (either a or b) that could cause clumping of type AB cells. Consequently, even for AB individuals, it is always best to use donor blood of the exact same type as the recipient blood. If the matching type is not available and type A, B or O is used, it should be transfused very slowly so that the donor blood is well diluted by the recipient’s larger blood volume.

Similarly, because type O blood lacks antigens A and B, it would seem that this blood type could be transfused into persons with blood of any other type. For this reason, persons with type O blood are often referred to as universal donors. Type O blood, however, does contain both anti-a and anti-b antibodies, and thus, if it is transfused into a person of a different blood type it should be done slowly to minimize large clumping reactions.

The bottom line for transfusion is that blood types should be matched for transfusions.

Blood Typing

ABO blood typing is based upon the clumping phenomena of bloods of mixed types. Blood sera antibodies can be isolated from other components of the blood and then used as blood typing sera. Antibodies-b (called Anti-a sera), for example, would clump red blood cells containing A-antigens (type A). Anti-b sera would clump type B blood. Clumping will occur in both sera with type AB blood and in neither sera with type O blood.

In the ABO blood typing procedure, drops of blood are first secured following sterile procedures. A drop of blood is placed in a drop of anti-a sera and another drop is placed in a drop of anti-b sera. The drops are then observed for clumping. The pattern of clumping or non-clumping is interpreted and the blood type determined. The following patterns occur for the various blood types:
(Note: In this laboratory, simulated chemical reactions will be used to identify blood types rather than clumping.)


Simulated antibody A, 8 drops
Simulated antibody B, 8 drops
Simulated blood, type A, 10 drops
Simulated blood, type AB, 10 drops
Simulated blood, type B, 10 drops
Simulated blood, type O, 10 drops
Unknown blood-soaked items for Part II
Pipets, Beral-type, 6
Spot plate

Prelab Questions

  1. What are the four blood types in the ABO Blood Typing System?
  2. Explain the difference between blood types AB and O.
  3. What are genes? Alleles?
  4. What is dominant, recessive and codominant?
  5. What is phenotype? Genotype?
  6. Can a mother with type B blood have a child with type A blood? Explain.
  7. Can a father with type O blood have a child with type A blood? Explain.
  8. What are antigens? Antibodies?
  9. What determines blood type in the ABO Blood Typing System?

Safety Precautions

This lab does not use any real blood components and therefore, poses no greater risk than the handling of small quantities of chemicals involved in the tests. Wear chemical splash goggles, chemical-resistant gloves and a chemical-resistant apron. Wash hands thoroughly with soap and water before leaving the laboratory.


Part 1. Simulated Blood Typing Tests

  1. Rinse a spot plate with distilled water.
  2. Place 5 drops of each known blood type in the wells of the spot plate as shown in Figure 1. Use a separate, clean Beral-type pipet for each blood type.
    {12177_Procedure_Figure_1_Placement of blood types on spot plate}
  3. Add two drops of antibody A to the top four wells using a clean Beral-type pipet. Record the results on the Blood Stains Worksheet.
  4. Add two drops of antibody B to the bottom four wells using a clean Beral-type pipet. Record the results on the Blood Stains Worksheet.
  5. Answer the questions in Part I of the Blood Stains Worksheet.
  6. Consult your instructor for appropriate cleanup and disposal procedures.
Part 2. Testing Crime Scene Blood
  1. Your instructor will provide crime scene blood samples or have you collect them. Follow instructions carefully to determine the blood type of the samples and use the results as data for your crime scene investigation.
  2. Record all results in Part II of the Blood Stains Worksheet or as directed by your instructor.
  3. Consult your instructor for appropriate disposal procedures.

Student Worksheet PDF


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