Phool Jahan was having an affair with her cousin Achchan and both the families were ready for the marriage, but the girl's brother Gul Hasan and Mohammad alias Nanhu were against it, Senior Superintendent of Police Bablu Kumar said.
He said that on August 17 afternoon, Gul and Nanhu saw Phool Jahan visiting Achchan's house in Kalan village.
Agitated over this, Gul and Nanhu beheaded Phool Jahan and moved around the village carrying her head, the SSP said.
Kumar said the second accused would be arrested soon.