Valentina Novozhyonova, 23, checked into a resort on the southern island on February 11 and mysteriously disappeared four days later.

Police yesterday found a black slipper near the resort where she was staying but it was not clear whether it belonged to her.

Prior to her disappearance, her social-media posts revealed that she had been free diving during her holiday.

Police believe she might have had an accident while diving.

“Th ongoing investigation reveals she never hired a boat to go to diving spots. She swam to the spots herself,” a source said.