Nicholas Salvador was armed with a wooden pole and a machete, the court heard
A man who beheaded an elderly woman in her garden in an attack of "extraordinary brutality" has been cleared of murder on the grounds of insanity.
Nicholas Salvador killed 82-year-old Palmira Silva in September last year.
The 25-year-old believed he was seeing demons and "ran amok" through back gardens in Edmonton, north London before the attack, the court heard.
He will be detained indefinitely in a psychiatric hospital.
Palmira Silva's granddaughter Christina recalls the "nightmare" of hearing the news
Recorder of London Nicholas Hilliard QC told Salvador: "It is established beyond any doubt that you killed Mrs Silva in an attack of extraordinary brutality and ferocity.
"You thought you were encountering some demonic force which had taken on a human form. You could not have been more deluded.
"Nobody who saw it could forget the mild and trusting way Mrs Silva approached you over the wall while you were brandishing a knife."
Salvador's barrister said he was regarded as a decent man when he was not unwell
He said Mrs Silva was a "gentle, intelligent" lady who deserved to live her life "in peace and with security, proud in the achievements of others".
The Old Bailey heard Salvador vaulted into Mrs Silva's garden and, after a brief exchange, stabbed her repeatedly before cutting her head off.
Her granddaughter Christina Silva said: "You don't really know how to comprehend this happened, you still to this day think it is a big nightmare and you think you're going to wake up and everything will be fine."
She added: "Every day I wake up and replay the attack on my grandmother in my head. Since the attack I have completely changed from the person I used to be.
"The thought of being alone in the house terrifies me."
Palmira Silva's daughter said she was "very much the glue that held us all together"
Mrs Silva's daughter, Celestina Muis, said her mother's death had devastated the whole family who "no longer feel safe".
She said: "Palmira had a full life, loving her children, grandchildren and great grandchild. She was very much the glue that held us all together.
"Our lives have been torn apart knowing what happened to my mother."
Mrs Silva's family wiped away tears and hugged each other as the verdict was read out in court.
CCTV footage showed Salvador killing two cats before targeting Mrs Silva. He lost his job three days before the incident, and smoked skunk cannabis, the court heard.
His trial heard two psychiatrists agreed he was suffering from paranoid schizophrenia.
When he carried out the killing, he believed Mrs Silva was a supernatural entity, either Adolf Hitler back from the dead or a demon who had taken the form of an old lady, jurors heard.
The court heard Salvador had lost his job in billboard advertising three days before the killing
He was staying with friends three doors away from the Italian-born grandmother's house in Nightingale Road when he went on the rampage.
Salvador was remanded in custody at Belmarsh prison but, due to his mental state, he was moved to high-security Broadmoor Hospital.
Enfield Inspector Doug Skinner said the there were children playing in nearby gardens when Salvador was jumping over fences.
"We genuinely thought he would kill those children and we were filled with utter terror," he said.
In court, Salvador's barrister Bernard Richmond said he was regarded as a decent man, when he was not unwell.
He said: "Mental illness in whatever circumstances can be terrifying for the person and one of the things we have to bear in mind that, after this case is finished, he will have to continue, as his mental state improves, coming to terms with the horror of what he did when he was unwell."