Since the James Foley beheading video was released by the Islamic State on Tuesday night, people have been urged not to share or view the video itself, or images from it, out of respect for the American freelance journalist's family - and to not spread what amounts to Islamist propaganda.
But now there is another reason to stay clear of the horrific footage - watching it could be illegal.
Scotland Yard has issued a statement warning that "viewing, downloading or disseminating extremist material within the UK may constitute an offence under terrorism legislation".
The relevant legislation is sections one and two of the Terrorism Act 2006, which can be viewed in full here.
The Metropolitan Police said its Counterterrorism Command (SO15) was investigating the contents of the video itself.
Foreign secretary Philip Hammond acknowledged earlier today the man filmed murdering Foley, 40, spoke with what sounded like a British accident.
"We have been saying for a long time that there are a significant number of British nationals in Syria and Iraq operating with extremist organisations," he told BBC Breakfast.
“That's one of the reasons why this organisation represents such a direct threat to the UK's national security."