A kidnapping case in the Eastern Cape has turned into a murder investigation after the gruesome discovery of the bodies of the three people that went missing.

A 71-year-old grandmother and her two granddaughters, aged 16 and 17 were kidnapped from their home near Tsomo on Monday.

Their bodies were discovered in the Mhlahlane River.

Police divers recovered the bodies which were tightly bound with chains.

Police spokesperson, Namhla Mdleleni, says the motive for the crime is unknown and the police are calling on people with information to come forward.