The rise of “0 to 100” killers who go from watching torture, mutilation and beheading videos in their bedrooms to committing murder suggests there could be a link between extreme violence online and in real life, experts have said.

Criminal justice experts advocated a new approach, inspired by counter-terrorism, to identify an emerging type of murderer with no prior convictions, after cases such as Nicholas Prosper, who killed his mother and siblings and planned a primary school massacre.

Jonathan Hall, the government’s independent reviewer of terrorism legislation, said there was a “new threat cohort” combining terrorists who were radicalised online and those who had “gone down a rabbit hole and into a dark world”.

He said: “There are quite a lot of similarities: they are isolated loners, boys rather than girls; the internet is obviously central; quite a high proportion have neurodivergence.