July 2015
The remaining line of inquiry is centred around a letter asking for assistance sent from UK investigators to the Portuguese Public Prosecution Service in July 2015.
The statement from the Attorney General's office said confirmed they had received the letter in July, and said the request will be sent to the Criminal Investigation Police (PJ) for them to look in to.
The spokeswoman would not comment on the nature of the request.
October 2015
Madeleine McCann case: Police team cut to four
April 2016
Madeleine McCann case: One line of inquiry remains
Police are following one remaining line of inquiry into the disappearance of Madeleine McCann, Scotland Yard boss Sir Bernard Hogan-Howe has said.
February 2017
In the 76-page ruling on the case – made public – they also said the archiving in 2008 of the criminal case into Madeline’s disappearance does not prove the McCanns are innocent.
They wrote: “It should not be said that the appellants were cleared via the ruling announcing the archiving of the criminal case.”