Studies in Bloodstain Pattern Analysis

Michael E. Dickerson
Home     What is BPA?     Types of Bloodstains     Experiments     About Me     Contact Me      
BPA Tools     Detection & Enhancement     Biological Hazards     Bloodstain Measurements     Bloodstain Directionality     Bloodstain Microscopy      
Detection & Enhancement
 
 
The intended use and design of Hemastix ® is the detection of blood in the urine; however, these testing strips have become quite common in determining whether or not a suspected stain is blood. These testing strips will not distinguish between human or animal blood and its results should be treated as presumptive and not positive. The reagent strips detect the peroxide-like activity of hemoglobin in a given substance. Before using the strip it is best to moisten the reagent pad with a drop of distilled water.
 

      

Hemastix ®, Bottle of 50

 
    
                                                                        
                                   Negative Result!                                                 Positive (Presumptive) Result - Green
                                                                                                                              
 
Another presumptive test for the presence of blood is the use of Phenolphthalein (Kastle-Meyer Test). Again, this test does not distinguish between human and animal blood; therefore, your sample would need to be sent to a lab for further testing.  After you swab the suspected stain, the order of the chemicals are: one (1) drop Alcohol, one (1) drop Phenolphthalein, and finally one (1) drop Hydrogen Peroxide. If you get a pink coloration after applying the drop of Phenolphtalein, this indicates a false positive. Additionally, if you're swabbing a dried stain you can first moisten the swab with a drop of alcohol.
 
 
Basic Phenolphthalein Test Kit
 
 
        
                                       Stain to be analyzed                                                Presumptive positive (bright pink)
 
 
    

Here's another test you can do and it's by BLUESTAR ® FORENSIC. It's called the HEXAGON OBTI TEST. This is a two part test and is really simple to do.  Additionally, this test is specific for human blood. All that needs to be done is put your suspected blood sample in the provided tube/bottle and gently stir. Next, lay the test on a level surface and place two drops of the mixture which contains your suspect blood into the sample (S) well. Wait five minutes and check your results in the center window. Basically, you’re looking for two blue lines to appear; one that says test is working properly (Control) and the second for the presence of Human hemoglobin (or primate, Ferret or Skunk Hb).

 

 

 
 
 

                

              Mixture containing a suspect blood sample                               Positive result for Human Hemoglobin