By Jyotsna Singh
BBC News, Delhi
Such crimes normally occur in rural areas
Three men have appeared in court in Ghaziabad - a suburb of India's capital Delhi - in connection with the killing of their mother, police say.
The 55-year-old woman was allegedly beaten to death by her sons who thought she was possessed by an evil spirit.
Police are investigating the incident which has shocked residents.
Though similar incidents are sometimes reported from rural India, such a crime being allegedly committed by well-educated city people is rare.
'Knocking her head'
"A case has been filed under a law relating to culpable homicide not amounting to murder," Senior Superintendent of Police in Ghaziabad, Deepak Ratan, told the BBC.
He said four people, including three sons of the woman, were arrested on Sunday.
Mr Ratan said the sons were well educated - one has an engineering diploma while the other is studying business management. The third is a senior school student.
The sons said they started beating their mother in order to rid her of the evil spirit of a relative who died a few months ago, Mr Ratan said.
The incident took place during a family gathering when, according to eyewitnesses, the mother started behaving strangely, knocking her head against the wall in front of the guests.
Police said they had reports that the woman was mentally unstable.
The incident has horrified the neighbours.
In remote rural India, sometimes women are branded as witches are killed, but what many find shocking is that such a crime has been allegedly committed by well-educated people so close to the capital Delhi.
Experts say a majority of mental illnesses, even in urban India, are passed off as a result of being possessed by evil spirits and the patients in most cases are never offered any treatment.
Reports suggest nearly 1% of India's over one billion population suffer from serious mental illnesses, while another 10% suffer from some degree of mental health problems.
Experts also point out that with only 3,500 trained psychiatrists available in the country there is an acute shortage of specialist help.