Final answer:
The evidence found by Ed and Joe at the murder site is not specified in the provided text. The text explains a methodical approach to forensic analysis, likening it to how chemists gather observable evidence to theorize about the unobservable.
Step-by-step explanation:
The specific evidence that Ed and Joe find at the murder site is not mentioned in the given text. The excerpt provided discusses how the absence of feet in skeletal remains could be explained by the removal of shoes during preparation for burial, rather than by a violent act at the time of death.
Similarly, the analogy in the second paragraph compares this method of investigation to how chemists collect evidence in the laboratory to form theories about unobservable properties. The passage suggests a methodical approach to deciphering evidence, rather than providing concrete details about what Ed and Joe found at the murder site.