Chilling moment killer imitates firing gun as he prowls around family home before shooting dead his mum & siblings

THIS is the chilling moment a killer teen imitates firing a gun before he shot dead his mum and two siblings at his family home.

Nicholas Prosper filmed himself in the kitchen of the flat in Luton prowling around in a bright yellow bucket hat and jacket.

Bedfordshire Police Nicholas Prosper imitated firing a gun before shooting dead his family[/caption] PAJuliana was found at home in September[/caption] PADaughter Giselle, 13, was among the victims[/caption] PASon Kyle...