New Delhi: Police Monday said the killing of an elderly couple and their attendant in southwest Delhi's Vasant Vihar might have been carried out by a man and a woman known to the attendant. It is also suspected that the accused had come with an intention to harm the nursing attendant, but ended up killing the couple to eliminate witnesses, they said. The bodies of the elderly couple, Vishnu Mathur (78) and Shashi Mathur (75), and their nursing attendant, Khushbu Nautiyal (24), were found with their throats slit on Sunday morning.

According to police, the accused are believed to be acquaintances of the nursing attendant and she facilitated their entry into the house. "We have very strong clues that the friendly entry was facilitated from the side of the nursing attendant," a senior police officer said. The CCTV camera captures the movement of a man and a woman close to midnight. Fifteen teams have been formed to trace the accused involved in the killing. So far, four suspects have been detained and are being questioned, the officer said.

Joint Commissioner of Police (New Delhi) Anand Mohan said the investigation is in progress. "We are working on it and various teams have been formed which are working on the leads," he said. Post-mortem examination of the three bodies have been done. Nautiyal belonged to Uttarakhand and her body was handed over to her family after the autopsy, police said. The daughter of the elderly couple has not raised any suspicion on anyone so far, the officer said.

Blood samples have been sent for forensic examination. Police have ruled out robbery as a motive. No alcohol bottles were found in the room but a half empty glass with leftover liquid, suspected to be alcohol, was found from the crime scene, he said. Call record details of Nautiyal have been accessed. Dump data of cellphones active in the vicinity of the house have also been accessed, police said.