Final answer:
Bloodstained evidence should not be stored in an airtight container as it needs to dry out to prevent the growth of mold or bacteria, which could degrade the evidence.
Step-by-step explanation:
The type of evidence that should NOT be stored in an airtight container because it could cause damage is bloodstained evidence. Bloodstained materials need to dry out; otherwise, placing them in an airtight container can result in the accumulation of moisture, which can cause the growth of mold or bacteria that might degrade the evidence. This makes the biological evidence difficult to analyze and could compromise the results of any forensic investigations. Other types of evidence such as a piece of glass or a bullet casing do not have the same requirement and can typically be stored in airtight containers without issue. Charred evidence from a fire may also need to dry out to prevent further degradation, but the moisture concern is particularly critical with bloodstained materials.