Police are comparing soil from a reservoir in Portugal to samples found in main suspect Christian Brueckner’s camper van, reports have claimed.
Investigators believe Brueckner visited Barragem do Arade reservoir just days after Madeleine’s disappearance.
Detectives hope comparing the samples can prove the 45-year-old was in the area at the time the toddler vanished.
An insider told The Daily Mirror that police can “close the net” around Brueckner if the soil samples reveal a “positive match”.
Madeleine McCann went missing in 2007PAOne well-placed source said: “Photos led German police investigating Maddie’s disappearance to the reservoir.
“One of their focuses now is to close the net around Brueckner by showing through soil sample analysis that his van was there.
“A positive match of the soil they already have from the vehicle with the earth they removed during the search last week will be another important piece of evidence against him.
“It will be a slight setback if the forensics people don’t get a match but at this stage investigators remain hopeful.
The search lasted three daysir
PA“The search that took place last week would never have been requested and authorised if the motive for it hadn’t been well supported.”
Brueckner, who is serving his sentence for raping an American pensioner in Portugal in 2005, has not yet been charged over Madeleine’s disappearance.
Experts have voiced concern about how easy it will be to analyse “traditional” evidence 16 years after Madeleine vanished.
However, German prosecutors first linked Brueckner to the remote beauty spot through photos that have not been made public.
Madeleine McCann (left) and prime suspect Christian Brueckner (right)
PAGerman and Portuguese search teams spent three days at Barragem do Arade last month.
British investigators conducted a separate search on waste ground in Praia da Luz in June 2014.
The reservoir is around 40 minutes away from the Praia da Luz holiday apartment which the McCann’s visited in May 2007.