SF Short story/novella: Dogon ceremony turns twin sisters into predatory reptilian ancestors.

[Richard Listener]

An investigator visits a jailed woman with reptilian features - story emerges that she and her twin sister, against warnings, undertook a Dogon ceremony that caused their reptilian DNA to activate, turning them into telepathically controlling predators (when linked). After one sister is taken out by a rifle shot, the other is incarcerated and interviewed.