According to the Dhar district police superintendent Aditya Pratap Singh, four men (all relatives and neighbours of the widow) have been booked.
The accused suspected that the black magic being practised by the couple was the reason for keeping their family members unwell.
Dr Mishra began a crusade against witchcraft (also called tohni) and other inhuman social practices by holding lectures to create awareness at schools.
The culprits tied the two women with ropes and threatened to kill them if they didn’t leave the village within a day.
Police seized the skeleton and skull of the woman, Kuni Jerai (55), on Friday, said police.
Villagers Rameyapalli alleged abnormal behaviour by some young girls after Ramaraju Reddy and two others performed a puja some days ago.
The locals said the miscreants killed the woman after suspecting her to be practising witchcraft.