Why is Festus, Missouri so murdery?

Festus sits in Jefferson County in eastern Missouri, about forty minutes from St Louis and close to the Mississippi, one half of the Twin Cities pair with Crystal City next door. It got a post office in 1883, counted 11,910 people in 2020, and took its name, supposedly, from the first proper name a local businesswoman found in the Bible.

Seven murders in four episodes fall within twenty-five miles, and they spread wide: one in Festus itself from 1990, two in different towns in September 1993, twenty-one and twenty-two miles out, and one in a small Illinois suburb across the river in 2009. Episode 415 carries three of the seven victims by itself, so a single case does a lot of the lifting, but the rest are singles across three decades. This counts the show's cases, not the area's crime rate; the show picks the towns, which is rather the point.