An elderly woman and two cats were beheaded by a man who went on a 45-minute rampage through a neighbourhood, a court has heard.
Palmira Silva, 82, was in her back garden when she was attacked by paranoid schizophrenic Nicholas Salvador, 25, who was armed with a wooden pole and a machete, the Old Bailey was told.
Heavily-built Salvador had also smashed his way through garden fences and broken into a neighbour's house before he was finally arrested during a violent struggle with police in which he was tasered six times.
Opening his murder trial, prosecutor Jonathan Rees QC told the jury there was no dispute that he killed Mrs Silva at her home on September 4 last year.
At the time of the killing, Salvador was living three doors away from Mrs Silva in Nightingale Road, Edmonton, north London.
At 1pm, he armed himself from the house he was staying in and killed two of his hosts' cats, because he thought they were "demons", the court heard.
He made his way through a few back gardens then smashed his way into another house and attacked a car containing two members of the family who he was living with.
Next, he went back through the house and into an alleyway that ran alongside Mrs Silva's home, jurors were told.
The victim had wandered into her back garden and approached Salvador who leapt over a wall into her garden and attacked her, repeatedly stabbing her with the knife before cutting off her head.
Afterwards, the defendant ran through a series of gardens at the back of the terraced houses, tearing down fences as he went while police tried to evacuate nearby residents.
He was finally arrested by armed officers in the front room of another house in Nightingale Road "after a violent and chaotic struggle", Mr Rees said.
Salvador had been showing signs of mental illness, repeating phrases such as "red is the colour" and "I am the king".
In the weeks before, he had shown signs of "odd behaviour" and had developed an interest in "shapeshifters" - supernatural entities that can physically transform into another being or form.
Mr Rees said that psychiatrists would give evidence that he was suffering from paranoid schizophrenia.
Salvador denies murder by reason of insanity.
The events leading to the horrific killing were recorded on a camera which was mounted on a police helicopter which happened to be passing overhead, the court heard.
Mr Rees told jurors that they would be shown some of the footage - but not the images showing the attack and its immediate aftermath.
After being charged with Italian-born Mrs Silva's murder, Salvador was remanded in custody at Belmarsh prison but due to his mental illness he was moved to high-security Broadmoor Hospital.
