Pakistan, Aug. 9 -- Despite the labyrinth of harrowing tales of abuse around us, a family in Karachi would hardly have thought twice about their relative, a 17-year-old, frequently visiting their house and taking their toddler daughter outside to buy her treats.

On Tuesday evening, however, he brought her back unconscious. By the time the family rushed her to hospital, the one-and-a-half-year-old was dead. An arrest has been made under Section 302 of the Pakistan Penal Code, while initial medico-legal findings point towards sexual assault. Yet, as the final post-mortem report is awaited, social media is abuzz with hashtags and calls for swift justice.

Horrific as that sequence is, its most unsettling detail lies in its familiarity. That...