The incident took place in Kathaolia village late last night when Mohd Ishaq (40) and Jehrunisha (22) was attacked by her brother Azeem-ur-Rehman with some sharp-edged weapon, they said.
Ishaq died on the spot while Jehrunisha was admitted to hospital in serious condition.
Azeem was angry with her sister after she had gone into a live-in-relationship with Ishaq, police added.