COLOMBO, Sri Lanka—While monitoring the usual channels, Indian police stumbled upon something extraordinary: a detailed plot for what would become the bloodiest attack linked to the ISIS group in South Asia.
Police were investigating suspected sympathizers of the withered caliphate in southern India when a name they had no record of surfaced—National Towheed Jamaat, the Sri Lankan ISIS-backed extremist organization that authorities say conducted the coordinated Easter Sunday attacks on churches and hotels in Sri Lanka that killed more than 250 people.
