Nandini (16), who was having an affair with Aman (20), both residents of Abar village, went missing on Thursday last, but were recovered after two days and handed over to their family members, IG V P Tripathi said.
On Monday, Nandini was strangulated by her family members and later her body was disposed off in Rapti river, they said.
Later, the body of Aman was also recovered hanging from the ceiling in a house in Rajwapur village, he said.
Efforts are on to nab the absconding accused while the further probes are on, the IG added.