The girl, a resident of Purwa Mehdi village, had gone missing last evening, SP Prabhakar Chaudhary said.
The locals staged a protest on the Deoria-Gorakhpur road alleging that the girl was raped before murder, the SP said, adding the postmortem report was awaited to ascertain whether she was sexually assaulted before her death.
An FIR against unknown persons has been registered and investigation is on.