But the town police colluded with the vigilantes!

How can it be certain that the record isn't a post hoc fabrication. Or if not entirely, then at least embellished.

Looking the other way is quite different than planting evidence.

Nor feasible in this case. Even a town sheriff wouldn't be able to modify offline (1981) databases of multiple jurisdictions. Or have the endurance to manufacture plausible entries and histories for dozens and dozens of cases over decades.

A few hours research could likely pierce any misinformation.