A former Network Rail administrator has been detained indefinitely after he admitted killing his mother by setting fire to their home.
Beatrice Yankson, 59, died of burns and inhalation of fumes after she was pulled from the blaze at a flat in Holloway, north London.
Her son Joel Ellis, 36, also suffered serious injuries after he was found unconscious slumped against a bed upstairs.
Prosecutor Simon Denison QC told the Old Bailey that Ellis had obtained a container of petrol a few days before the fire and decanted it into bottles.
On October 26 last year, Ellis removed a smoke detector and used the petrol as an accelerant when he set fire to the flat.
In the wake of the blaze, two Samurai swords, two knives and a blank firing pistol loaded with cartridges were found in Ellis's bedroom.
Ellis had expressed remorse for the death of his mother, stating that he intended to kill himself in the fire and did not know she was home.
The court heard Ms Yankson had previously worked as an Imperial College administrator and had been a main carer of Ellis's brother, who has autism.
Ellis had been charged with murder but pleaded guilty to the alternative offence of manslaughter and arson.
The pleas were accepted by the prosecution after psychiatrists agreed he was suffering from depression and schizophrenia.
The court heard his struggles with mental health dated back to 2017.
Judge Richard Marks QC handed Ellis a hospital order without limit of time.
The judge said Ellis was suffering "very significant symptoms" of mental illness, including the paranoid belief that he had to burn himself so his body would be destroyed.