The accused identified as Mahaveer Prasad (32), a sub-inspector in Sriganganagar, allegedly raped the victim after giving her sweets laced with some intoxicant at her residence on December 12 last year, police said today.
The victim, who was living away from her husband, alleged that Mahaveer repeatedly raped and blackmailed her.
The police have booked Mahaveer under Section 376 of IPC.
Preliminary investigation has revealed that the accused and the victim were of the same batch and had received training together, police said adding, they were "good friends".