Final answer:
An investigator might ignore a bullet hole at a crime scene if it's deemed irrelevant to the burglary, is contaminated, or doesn't fit the burglar's modus operandi. Decisions are based on evidence priority, resources, witness reliability, and relevance to the core aspects of the crime.
Step-by-step explanation:
An investigator might ignore a bullet hole at a crime scene if it was determined to be irrelevant to the case at hand. This decision could be made in various circumstances, such as when there is overwhelming evidence pointing towards a different scenario or when the evidence of the bullet hole has been contaminated or is known to be unrelated to the burglary.
Moreover, if the investigation is of a highly focused nature—such as a case where a specific modus operandi is being followed by the burglar and gunshot has no place in it—that piece of evidence might not be considered pertinent. Similarly, if a large number of tips and potential leads are present, as in the case of the sniper attacks in the DC area, law enforcement may need to prioritize certain pieces of evidence over others to manage resources effectively.
Also, in the provided scenario with the 140,000 tips leading to 35,000 possible suspects, the validity of some evidence may rely on eyewitness reports, which can be influenced by suggestibility, leading to the creation of false memories. This suggestibility may lead to focusing on certain evidence (like the white van) while disregarding others. Lastly, as with the examples of microscopic examination of furniture in detective work, only evidence that is directly relevant to the core aspects of the crime will be pursued with fervor.