Final answer:
The critical findings in 'Mr. Thompson's tent' are not clearly identified without additional context from the story being referenced. The provided excerpts present different forms of potential evidence in various scenarios but do not directly address Mr. Thompson's tent.
Step-by-step explanation:
The question seems related to a literature class, possibly focusing on a detective or crime story. In the provided excerpts, several items could be considered critical evidence found in various scenarios. These items include miscellaneous letters and papers, musical instruments, hidden microphones in ChapStick containers, a laminated prayer card depicting Saint Jude, two marijuana bundles and a .22 rifle, pottery from a cliff dwelling, the traumatic discovery of railway cars filled with corpses, and suggestive police identification procedures. However, without knowing the specific context of 'Mr. Thompson's tent', it is challenging to pinpoint which, if any, of these examples directly relates to the critical findings in Mr. Thompson's tent.
More context is needed on 'Mr. Thompson' and the circumstances surrounding his tent before one could accurately determine what investigators found that became critical. The details provided in the examples do show how various evidence is crucial in different investigative scenarios, illustrating the process of gathering and interpreting clues in literature.