The man seen on CCTV is described as dark skinned, with a full beard, wearing a light baggy top with a satchel across his chest.
Detective Chief Inspector Sheila Stewart said: "It is vital we track down this man who was in the precise area at the time Mariana was attacked and killed."
More top news
A total of 1.7 million attacks were carried out against more than 650,000 victims of which just over 52,000 were in the UK.
The men were using ropes to lever the sofa up to the first floor apartment because it was too large to fit through the doors.
He's not even halfway.