Why is the Pearisburg, Virginia area so murdery, by episodes?

Pearisburg is the seat of Giles County in north central Virginia, with 2,878 people. It was founded in 1808, when the county was established, and named for a local landowner who gave 50 acres so a town could grow around the courthouse. He had commanded Virginia cavalry in the War of Independence and carried a wound in his shoulder. The Appalachian Trail runs along the ridge above the town, and one of the two episodes here starts at a shelter up there.

The Pearisburg area takes in Radford, 17 miles away. The five murders are spaced across three decades: June 1980, May 1981, May 2008. Four of the five sit in Episode 555, and two of its cases are 27 years apart.

That episode opens in 1981 with two social workers from Maine, both 27, hiking the whole 2,050-mile trail to raise money for the disturbed children they looked after. They bedded down for the night at a shelter above Pearisburg, where they had been seen with a man using a false name.