Why is Lancaster, Texas so murdery, by episodes?

Lancaster is about 25 minutes from Dallas, in Dallas County, and it stayed a small town for most of its life. Around 600 families settled Peter's Colony between 1841 and 1844. Advertising in Kentucky, Illinois, Missouri and Tennessee brought them, and the first of them arrived from Illinois in 1844. In 1852 a settler bought 430 acres from a founder's widow and laid the town out to look like his Kentucky hometown. Two bank robbers took more than $6,000 from the local bank in 1934. By the 1980s Lancaster still held perhaps eight to ten thousand people. It has more than 41,000 now.

All seven victims come from one episode, 609. They are spread across four cases, all in Lancaster, from November 1978 to September 1986, with two of the cases in 1986.

That puts Lancaster at rank 140 overall and second in Texas.