A 3-year-old boy was found dead alongside his mother and father at their West London home after a "murder-suicide".
Scotland Yard today, October 6, said they forced entry into the fourth-floor flat on Clayponds Lane in Brentford shorty before 1am this morning.
Officers found Kuha Raj Sithamparanathan, 42, suffering with stab wounds as well as the bodies of his wife Poorna Kaameshwari Sivaraj, 36, and their three-year-old son Kailash Kuha Raj.
Kuha, 42, was treated by paramedics but was pronounced dead at the scene.
Detective Chief Inspector Simon Harding, from the Met's specialist crime command, said: "Although we are in the infancy of this investigation, it appears that Poorna and Kailash had been dead for some time.
"This is a murder investigation and my team will work diligently to establish the sequence of events that led to their murders and the death of Kuha Raj Sithamparanathan.
"Our initial enquiries have established that Poorna and Kailash had not been seen or heard from for some time, perhaps since around September 21."
It is believed that Kuha stabbed himself when officers entered the property.
The family's Cockapoo dog, which they would often be seen walking, is also believed to have been killed.
Scotland Yard said it had been responding to concerns about the occupants' welfare.
Police attended the address "several times" in the early hours of Monday but did not get a reply and after speaking with other residents became increasingly concerned and decided to try force entry, the Met said.
Shocked neighbours earlier today recalled hearing heated arguments at the Sithamparanathans' home over the past few months.
One neighbour who lives on the fifth floor told MailOnline: "During the lockdown I could hear them arguing a lot.
"I could hear her screaming at her husband, telling him to take his medicine. Then on another occasion, he threw them out of the window, and I looked down and could see them on the ground."
Another neighbour added: "Things got really bad between them, especially during the lockdown.
"They are one of the few couples with a young child in our block and you could hear the screaming at each other, sometimes for very long periods."
The couple married in Kuala Lumpar in 2015. They owned a pet dog that is believed to have also been killed.
Jamila, who lives in a neighbouring block said: "It's tragic. They loved their dog and I'd see them all the time taking him out for walks. They were a lovely family and none of this makes any sense.
"The officers told me that there was blood all over the flat and that the dog had also been killed."
Forensic officers in protective suits were spotted entering the police cordon this afternoon.
Next of kin have been informed of the deaths and post-mortem examinations are scheduled to begin on Thursday, October 8.
