We might consider race of the victims.

The case of the Freeway Phantom has faded into history — but not everyone has forgotten.
— Read on www.washingtonpost.com/lifestyle/magazine/six-black-girls-were-brutally-murdered-in-the-early-70s-why-was-this-case-never-solved/2018/05/21/c74d26ec-4e22-11e8-af46-b1d6dc0d9bfe_story.html