Bobokulova, a mother-of-three allegedly strangled defenceless Nastya Meshcheryakova, who had learning difficulties, before cutting her head off with a kitchen knife.
The little girl’s lifeless body was found in a cot at the flat.
The 38-year-old nanny told police she had been haunted by “voices” and was driven mad after learning her husband had started a new family in Uzbekistan while she worked in Russia.
Horror erupted close to Oktyabrskoye Pole metro station in the northwest of the Russian capital yesterday after eyewitnesses reported a woman shouting “I’m a terrorist” while wandering the streets brandishing the head of a dead child.
A spokesman from the Investigative Committee of Russia said: “Given the clearly inappropriate behaviour of the person detained, investigators immediately appointed her to a forensic psychiatric examination to determine their ability to realise the significance of their actions and deeds.”