Today's statement from the British, US and Libyan governments follows an interview ITV News did earlier this week with the justice minister from Libya, in which he said he was now willing to cooperate with police in the US and UK.
The Foreign Office has now welcomed that development and said that it looks forward to visiting Libya in the new year and to getting access to information and witnesses to progress their investigation.
Scotland's Lord Advocate has previously said there are still people out there with blood on their hands for this atrocity.
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"We've never actually spoken so publicly about her," the Duke of Cambridge said. "But we felt that this was the right time to do it."