A stretch of land in the Praia da Luz resort where Madeleine McCann went missing in May 2007 has been roped off as British police begin searching for forensic evidence.
"Obviously there is the chance her body could be found"
A source said to The Mirror: "This is a critical time in the British investigation and could provide the big breakthrough in the case.
"Obviously there is the chance her body could be found.
"That is a nightmare scenario for her family, but it would also bring closure.
"They understandably have to remain positive and assume Madeleine is alive, but the dig raises the possibility of finding evidence that she is not."
Officers are expected to use radar and search dogs before excavation gets underway - and a forensic archaeologist has arrived at the area not far from the holiday apartment where Maddie disappeared.
Two weeks ago Scotland Yard's Assistant Commissioner Mark Rowley warned that developments like those seen today will not necessarily “lead to answers that will explain everything”.
He said: “In the forthcoming weeks we are going to be going to a substantial phase of operational activity on the ground in Portugal.
“It's something that you would expect in any major inquiry.
“A thorough serious crime investigation works systematically through all the credible possibilities, and often in an investigation you will have more than one credible possibility.
“Therefore, just because we're doing a substantial phase of work in the forthcoming week doesn't mean that it's going to immediately lead to answers that will explain everything.”