Carole Harrison, 73, was discovered in her home in leafy Teddington, South West London, following a blaze in the early hours of Wednesday.
Detectives from the Met's Homicide and Major Crime Command are investigating. It is the sixth murder inquiry launched in London in a week and the tenth this month.
The capital has been plagued by bloodshed this year with knife crime and shootings on the rise as cops struggle to deal with the violence.
A surge in drill rap music and moped crime saw London's homicide rate momentarily overtake that of New York.
Smiling at the camera and posing with pals, these are the 100 victims slaughtered in Lawless London this year.
1. Kyall Parnell
The 17-year-old died from a single stab wound to the heart after being attacked in front of horrified New Year's Eve revellers in Tulse Hill, South London.
Kyall was one of four people knifed to death over the New Year period and a murder probe was opened in 2018.
An inquest into his death in January heard how thugs had shouted "stab him, finish him off" before Kyall was killed.
2. Steven Narvaez Jara
Student Steven, 20, had devoted his life to becoming a pilot but his dream was ripped away on New Year's Day when he was knifed to death.
He had been embroiled in a row at a house party in Old Street, North London, and became the first person to be killed in 2018.
Ecuador-born Steven studied physics and aerospace at the University of Herefordshire.
3. Elizabeta Lacatusu
The 20-year-old was stabbed 19 times by jealous ex Genu Armeanu in Redbridge, East London, on January 3.
Her 45-year-old killer, who was convicted of murder in June, committed the horrific act "out of love" after become obsessed with her in the final days of her life.
Mum-of-three Elizabeta died within minutes after being stabbed in the neck and torso, causing serious injuries.
4. Vijay Patel
Shopkeeper Vijay was attacked in a row over Rizla papers in Mill Hill, North London, on January 6.
The 49-year-old had refused to sell the papers to three teenagers before he was punched in the chest outside his shop.
Mr Patel's brother Prakash, 47, said: "He was the greatest man in the world. He died trying to protect the shop."
5. Daniel Frederick
The 34-year-old was stabbed to death in Hackney on January 8 after attending a hospital appointment with his pregnant partner.
Daniel was ambushed as he walked home in an "unprovoked attack".
In a heartbreaking appearance on the BBC's Victoria Derbyshire Show, his sister Louise Samuels broke down in tears as she described him lying in intensive care.
She said: "They just had him there pumping in blood…He had a tear that came down his eye and I asked if he was crying and they said 'I don't think so'.
"And then a tear came down again and I said: 'You know that you're going so…don't be afraid to go'."
6. Harry Uzoka
The successful male model, 25, was murdered by a catwalk rival who stabbed him to death with a machete after bragging he slept with his girlfriend.
George Koh, 24, had arranged with a fight with Harry on social media with chilling CCTV footage showing him chasing him down in Shepherd's Bush, West London, on January 11 with two accomplices.
Along with Merse Dikanda and Jonathan Okigbo, both 24, the killer took at least three knives, including a machete.
Koh and Dikanda were found guilty of murder while Okigbo was found guilty of manslaughter.
7. Seyed Azim Khan
Dad-of-seven Seyed, 49, was hacked to death with an axe by colleague Imran Muhammed, 30, who had lured him to the offices of A to Z Furniture and Carpets in Ilford.
Muhammed wrapped Mr Khan’s mutilated body in a blanket, before wheeling it for a mile in a Homebase shopping trolley through the streets of Ilford to a nearby cemetery.
Seyed was discovered eight days later hidden in undergrowth.
8. Yaya Mbye
Yaya Mbye, 26, died in hospital after being found collapsed in a children's playground on the George Downing Estate in Stoke Newington, East London, on January 28.
He had been chased through the housing estate by three men and repeatedly stabbed.
Passers-by gave first aid to Mr Mybe before he was rushed to hospital but he was pronounced dead an hour later.
9. Juan Olmos Saca
The 39-year-old was stabbed in the chest in Peckham, south east London, on the January 29 and died a week later in hospital.
10. Khader Saleh
Khader, 25, was knifed at Wormwood Scrubs prison on January 31.
11. Lily-Mai Saint George
The 11-week-old was found unresponsive at an address in Tottenham on January 31 and died at Great Ormond Street Hospital three days later.
A murder investigation was launched on April 16 when a 21-year-old woman and a 20-year-old man were arrested on suspicion of murder.
12. Hassan Ozcan
He was just 19 when he died from multiple stab wounds in Barking, east London, on February 3.
13. Kwabena Nelson
The 22-year-old youth worker from Tottenham, died after being stabbed near his home on February 3.
14. Hannah Leonard
Hannah, 55, was stabbed in a flat in Camden on February 8.
15. Sabri Chibani
The 19-year-old was stabbed in the chest in Streatham, south west London, on February 11.
16. Bulent Kabala
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