Murder squad detectives were today questioning a man who cared for his 100-year-old mother full-time after she was found stabbed to death.
The woman, named locally as Hannah Fitzgibbon, was discovered suffering a single fatal knife wound to her neck at her terrace home in Stepney, east London.
Her 61-year-old son Michael, a former black cab driver, was arrested and is being questioned on suspicion of murder.
Neighbours told police the victim was partially deaf, registered blind and had not left the home for several years.
It is understood police believe Mr Fitzgibbon may have been suffering from poor mental health.
Police and paramedics were called to Hainton Close shortly before 10am yesterday but were unable to save the elderly woman's life.
A Metropolitan Police spokesman said a post-mortem examination will take place later today at Poplar Mortuary.
A police spokesman said: "Next of kin have been informed. We await formal identification of the victim."
A spokeswoman for Tower Hamlets council refused to confirm that officials have begun a review of what support was given to the family.
She said: "We are not able to comment on individual cases. This is a police matter and we will help them in any way we can."