There often is a wide gulf between what one "knows" and what one can prove in court with evidence that would be accepted by the court. That gulf tends to be overlooked.
Exactly. What is sufficient to follow leads to better evidence in an investigation, is often not adequate for use in court. Lie detectors, for example. Another more pertinent one would be using a video gleaned from Twitter is good to run face recognition to point to somebody's name, but solid, testable evidence is needed for court, like credit card receipts in the vicinity of the video location.
