A “witch doctor” and his wife are the prime suspects in the murder of a family of five found along the side of a road in Fiji, authorities said.

Husband and wife Nirmal Kumar, 63, and Usha Devi, 54, their daughter Nileshni Kajal, 34, as well as Kajal’s daughters Sana, 11, and Samara, 8, were all found dead in the Nausori Highlands on Monday, the Australian Associated Press reported.

The only survivor, 1-year-old Samaira Kumar, was discovered by cops sitting on top of his grandpa’s corpse, the outlet reported.

The victims had no visible injuries, but a post-mortem examination indicated that they died of “an alleged substance” they had ingested, according to the report.

Police have detained and questioned a Christchurch, New Zealand, couple — who are known to the family — in connection with the deaths, according to the Fiji state-owned outlet FBC News.

A police official involved in the investigation told the Fiji Sun that the man is a “witch doctor.”

Though the man and woman, whose names were not released, have not immediately been charged, a stop-departure order has been issued for them, according to the reports.

Bhijiba Wati, Devi’s mother, went to the family’s home on the day of their deaths to get ready for a pooja, or Hindu prayer ritual.

When she found the home empty, she was concerned — and those worries turned to devastation when police confirmed what had happened.

“I couldn’t stop crying and asking God why such a gruesome killing has been done to them,” Wati told the Fiji Sun.