NEW DELHI—Policewoman Preeti Dhaka had been married nearly a month when she returned to a city pulsing with crowds of angry women last December protesting the brutal gang rape of a student on a bus.

Ms. Dhaka's regular beat was to protect women from crimes, and her heart was with the demonstrators her bosses sent her to restrain. "So many people are out here for her," Ms. Dhaka told her sister, referring to the rape victim. "She should get justice."

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