Thanks. I was wondering if Serial/Spree would fit. :)

A mass murder would also qualify for the serial/spree killer square.

Okay. I added the (?) because I wasn't sure. I figure that a serial killing is usually defined as multiple killings, taking place over a certain amount of time, whereas, in this book, the six women are all killed at the same time. Then again, there are two other murders that take place at different times as well.

I loved this one!