Why is the Iowa, Louisiana area so murdery, by episodes?

The Iowa area sits in the south-west corner of Louisiana, where the state runs out towards the Gulf of Mexico: Lake Charles twelve miles off, Lake Arthur twenty-three. Midwesterners from Kansas, Illinois and Iowa settled the land in the mid-nineteenth century, drawn by the railroad, and stayed for the rice and the cattle. Oil was struck in 1930, and the town has held at about 3,200 people. Lake Arthur, over in Jefferson Davis Parish, runs on the same rice and timber, and drew its own settlers from Iowa in the 1890s.

Three episodes carry the hotspot's seven murders, spread thin across the decades: July 1983, June 1991, June 2009. Episode 353 does most of the lifting, with five victims in Lake Arthur in what the hosts call one of the strangest cases they have covered. Episode 36 brings a single murder to Iowa itself, and episode 578 adds one more from Lake Charles. Not a hot streak so much as a slow drip across the same corner of the state.