A man held in connection with a suspected beheading of an 82-year-old woman in north London remains under police guard in hospital.
The body of Palmira Silva was found in a garden behind a house in Edmonton on Thursday afternoon.
Officers found her collapsed at the scene where she was pronounced dead.
A 25-year-old man was arrested on suspicion of murder by armed officers who discharged a Taser. Officers plan to question him when he is well enough.
An officer is also believed to have suffered a broken wrist during the arrest.
Police said they were initially called to reports of a man armed with a knife and eyewitnesses said he had attacked an animal, possibly a cat or a dog.