05. Forensic Chemistry

Coordinator: Prof. David Fisher and Dr. Sai Casado Zapico

Background 

While humans have an impact on the aqueous environment, water can wash away evidence at a crime scene. A crime could be committed outdoors, with biological evidence affected by environmental conditions such as rain and humidity. Moreover, after committing a crime, it is common for perpetrators to wash the clothes they wore at the time of committing illegal activities to alter or, if possible, destroy evidence of the crime. The clothes are commonly machine–washed using detergents or soaps until no body fluid stains are visible to the naked eye. Consequently, the ability to detect body fluids in these circumstances is crucial to reconstruct the events of the crime and potentially identify the perpetrator and, in some cases, the victim. Traditional methods may not be as effective; therefore, research and adaptation are required for reliable forensic analysis.  

This lab event is designed to promote critical thinking, problem-solving, and collaboration among students while addressing the relevant theme of human impact on the aqueous environment. By researching and applying forensic techniques, students will gain a deeper understanding of the principles of body fluid identification and the challenges posed when exposed to water and/or washing. 

Objective 

This event challenges teams to: 

• Research and select an appropriate method for locating and identifying body fluids exposed to water. 

• Prepare a Standard Operating Procedure (SOP) for their chosen method. 

• Locate and identify the body fluid on washing clothes: blood, semen, saliva, or a mixture. 

Safety 

• Personal Protective Equipment (PPE): Each team member must wear appropriate PPE, including gloves, safety glasses, and lab coats, throughout the experiment. 

• Chemical Handling: All chemicals must be handled in a fume hood to minimize exposure to hazardous vapors. Refer to the Material Safety Data Sheets (MSDS) for all chemicals used. 

• Solvent Use: Use flammable solvents in well-ventilated areas and keep away from open flames or heat sources. 

• Waste Disposal: Dispose of all chemical and biological waste according to established environmental safety protocols. Ensure proper segregation of waste. 

Prior to the Event 

1. Team Selection: Teams should consist of 3-4 high school students. 

2. Method Research: Each team will select and research a procedure for body fluid location and identification. This may include, but is not limited to: 

◦ Alternative Light Sources 

◦ Chemical methods 

◦ Immunochromatographic tests 

3. SOP Preparation: Teams will prepare a detailed SOP for their chosen methods, including: 

◦ List of materials and equipment 

◦ Step-by-step procedure 

◦ Safety precautions 

◦ Waste disposal methods 

4. Submission: The SOP must be submitted electronically one week before to the event for review by the judges. 

Day of Event 

1. Evidence Presentation: Each team will receive a washed garment with a stain.  

2. Location of the Body Fluid: Each team should locate the body fluid.  

3. Body Fluid Identification: Teams will use their pre-selected method and SOP to determine the body fluid: blood, semen, saliva, or a mixture of them.  

4. Presentation: Each team will prepare a brief PowerPoint presentation (2-3 slides) summarizing their methods, results, and conclusions. 

Judging Criteria (100 Points Total) 

SOP (30 points): 

◦ Clarity and completeness of the procedure. 

◦ Appropriateness of the chosen method for the evidence. 

◦ Thoroughness of safety precautions and waste disposal methods. 

Location of the stain (20 points): 

◦ Effectiveness of the method used to locate the stain.  

Body Fluid Identification (30 points): 

◦ Accuracy of the identification of the body fluid. 

◦ Justification of conclusions based on the results.  

◦ Proper documentation of the identification process.  

Presentation (20 points): 

◦ Clarity and organization of the presentation. 

◦ Effective communication of the method, results,