Rajesh Singh (40) had white spots on his body for which he consulted a 'tantrik' in neighbouring Hathipur village, they said.
The 'tantrik' prescribed some medicine to Singh and asked him to give it to his wife Geeta (45) and son Rohit (22) also, police said.
After consuming it, the three were taken ill last night and admitted to a hospital, where they died.
On being informed about the incident, police met their son admitted at the community health centre. He disclosed about the 'tantrik' before breathing his last, they said.