In the congested South Delhi district of Lajpat Nagar, houses stand cheek by jowl and most neighbours know each other.

So the brutal murder of a 62- year-old woman in her own home on a Sunday afternoon last week has sent shockwaves, not just through the area, but elsewhere in a city ravaged by the murder of five senior citizens in four weeks.

Vimla Ahuja lived with her husband Ashok, who is also in his 60s, in an apartment, but he was out at the time someone beat his wife to death. Her son Ajay, who lived in a flat above his parents, came down to find her body in a pool of blood and 100,000 rupees (S$2,000) missing. The police have arrested a man who used to work in a shop run by the couple for the crime and are investigating.

As the number of crimes against the elderly in India rise, so does the concern. Delhi is recording 89 crimes a year for every 100,000 senior citizens, defined as those over 60, according to the National Crime Research Bureau, the highest rate in India. But there were 18,714 crimes against senior citizens all across India in 2014. From 2001 to 2012, 40,753 elderly citizens, were murdered.

Last month in Delhi, a 71-year-old woman was found strangled in her house in south-east Delhi, while a 60-year-old woman was stabbed 22 times allegedly by a male domestic helper in south-west Delhi. All the cases are under investigations

The murders have sparked fears among elderly citizens in the city

"There is a sense of insecurity. So many incidents are taking place. Anything can happen. We feel very vulnerable,"' said Mr B. R. Thukral, an 82-year-old resident of Lajpat Nagar. His house was robbed of 300,000 rupees a month ago when he was visiting his children in the United States.

"Houses are touching each other and my neighbours all know me. There is a food vendor in front of my house, yet it was broken into in broad daylight," he said. "I have changed all the locks in the house and I have put up iron bars on my windows. At least I wasn't at home."

Unlike China or Japan with their ageing populations, only over 9 per cent, around 110 million, of India's population is over 60. But the number of elderly citizens is expected to double within the decade.

The traditional family support network, known as the joint family system where three generations live under the same roof, is splintering into smaller units as children often move elsewhere for work.

"The numbers of the elderly have gone up in the last 20 years (in India)," said Dr Anindya Jayanta Mishra, a sociology professor from the Indian Institute of Technology, Roorkee.

"The migration of children, decline of joint family system, weakening of social bonds and changing values have made this category of people vulnerable, not just to crime, but also to a lack of social security and problems with family members."

The crime rate against the elderly is so high that the police in the capital city have asked senior citizens to register with their local police station. They have also told them to register particulars of the domestic help they employ with the police.

Local constables are also supposed to visit the homes of the elderly for regular visits.

Non-profit groups have joined the effort, too.

Ms Sonali Sharma, director of communications at HelpAge India, said: "We keep telling older people that there are some basic security steps they need to take, like being connected to their local community, be in touch with immediate neighbours, put CCTV outside the house and not to keep valuables at home."

Mr Himanshu Rath, founder chairman at Agewell Foundation, said many of the elderly in India were not equipped to live on their own.

"We are also looking at a first generation of old people in India," she said. "For people who are in their 70s or 80s, their parents would have passed away in their 50s or 60s. Many of the elderly don't know how to be prepared for old age."

Still others felt not much was being done to prepare for the growing numbers of elderly citizens. A social stigma is attached to homes for seniors and there are few of them.

"The police have to play an active role and collaborate with the local community. There is also a need for private operators to construct better old-age homes," said Dr Mishra.

"They are not getting much attention, but they are the most vulnerable in Indian society."