Avoiding DNA Contamination
In forensic science, "contamination" is defined as the introduction of a foreign substance that is not related to the crime. This definition can be applied to crime scenes, bodies, and evidence. It is, unfortunately, extremely broad. Before we can discuss avoiding it, we must first define the different types.
"Self-contamination" is when the investigator or examiner contaminates the scene and/or evidence with his or her own DNA.
"Cross-contamination" is when the investigator or examiner contaminates a scene and/or evidence with DNA from another scene and/or evidence.
"Secondary contamination" is when the investigator or examiner inadvertently contaminates a scene and/or evidence with DNA from an intermediate object. It is not so much a type of contamination as it is a mode of contamination. This can happen from touching pens, cameras, or other objects that bear the DNA of the investigator or examiner or of the victim or perpetrator.
"Self-contamination" is when the investigator or examiner contaminates the scene and/or evidence with his or her own DNA.
"Cross-contamination" is when the investigator or examiner contaminates a scene and/or evidence with DNA from another scene and/or evidence.
"Secondary contamination" is when the investigator or examiner inadvertently contaminates a scene and/or evidence with DNA from an intermediate object. It is not so much a type of contamination as it is a mode of contamination. This can happen from touching pens, cameras, or other objects that bear the DNA of the investigator or examiner or of the victim or perpetrator.