Why is Libertyville, Iowa so murdery?

Libertyville is a small farming town in Jefferson County in south-east Iowa, platted in 1845 and originally known as the colony, about an hour and fifty minutes from Des Moines and three and a half hours from St Louis. It holds around 360 people; the whole county held only about 4,000, which makes it the sort of place where a seventeen-year stretch without a murder is worth remarking on.

Three episodes account for all eight of the show's murders within 25 miles, and they spread across three decades and three towns: a single case in Libertyville itself in 1991, five victims in one episode at Bonaparte in 2006, and two more at Agency in 2012. That Bonaparte episode does most of the lifting, carrying five of the eight on its own, while the other two add a case each. The distances are modest, 14 and 22 miles, so the cluster is really a handful of small towns scattered across the same quiet corner of the state.

This counts the show's cases, not crime statistics. The show picks the towns, and it has picked this corner of Iowa three times.