New Delhi, Feb. 4 -- Dipu Chandra Das, a 27-year-old Hindu garment worker, was accused in December by several Muslim colleagues of making derogatory remarks about the Prophet Muhammad. The accusations drew a violent mob to his workplace. He was beaten to death, his body hung from a tree and set on fire.

Across Bangladesh, Hindus watched the recorded images on their phones with dread. Protests erupted in Dhaka and other cities, with demonstrators demanding justice and greater protections. The interim government, led by Muhammad Yunus, ordered an investigation, and police said that about a dozen people were arrested.

But human rights groups and Hindu leaders say the killing wasn't an isolated act, but part of a wider surge in attacks on t...