After reading this chapter you will be able to:

• Discuss the three roles or functions of physical evidence in the criminal investigation process and describe how physical evidence can serve as direct evidence or circumstantial evidence in criminal investigations.
• Discuss the limitations of physical evidence.
• Identify the most important guidelines that should be followed in managing major crime scenes and collecting evidence from them.
• Discuss the evidentiary value of different types of physical evidence, especially biological evidence and DNA.
• Explain the Combined DNA Index System (CODIS) and how it increases the value of DNA analysis.
• Discuss the precautions necessary when collecting and handling biological evidence.
• Identify the specialty fields of forensic science.