According to police, the three sisters went missing from their home since February 14 following which the family lodged a complaint the next day.
Their bodies were found in a well on February 16 and police initially registered a case of accidental death.
However, postmortem on February 17 at district headquarters in Bhandara revealed sexual abuse and brutal killing, offences under relevant sections of the IPC for rape and murder were registered against the yet to be identified culprits.
Police inspector Prakash Munde was placed under suspension for dereliction of duty.
Additional DGP (Law and Order) Javed Ahmad, accompanied by Special Inspector General (Nagpur Range) Rajender Singh, visited Murwadi village today and issued directions to the police to speed up probe in the case.
Local leaders Nana Patole and Narendra Bhondekar have demanded a high level probe into the gruesome incident.
In Delhi, Prime Minister Manmohan Singh expressed concern over the incident and announced an ex-gratia payment of Rs. 10 lakh to their family.
Earlier in the day, the Centre sought from the Maharashtra government all details of the gruesome incident and submit a report.