The police are yet to make a breakthrough in the murder of an elderly school teacher who was found strangled to death in her house in Vivek Vihar here on Tuesday.

The police have so far questioned more than two dozen people who had been frequently visiting the victim, Anna Mammen (79), for the past few months, but there are no definite leads.

The police suspect that the assailant was not a professional criminal as he did not use any weapon to commit the murder and instead strangled the woman with the wire of a mixer-grinder wire. The entry to the house seems friendly suggesting the involvement of someone known to the victim.

“Though the elderly woman ran tuition classes in the morning and in the evening and a domestic help also visited her in the afternoon, the assailant struck at the time when she was usually alone. It suggests that the assailant knew the routine of the woman very well and chose the most opportune time to strike,” said a senior police officer.

The police have reportedly found that Ms. Mammen had got her house whitewashed three months ago and suspect their involvement.

Ms. Mammen, who was mother of criminal lawyer Rebecca John, was found murdered on the ground floor of her house in Block “C” Vivek Vihar around 3-30 p.m. The murder came to light when a watchman told Vinay Lal, a close relative of Ms. Mammen, that the rear gate of the house on the ground floor was open and asked him to close it.

Ms. Mammen had been English teacher at Mater Dei School on Tilak Lane for over 25 years.