Madeleine McCann German prosecutors say they ‘remain optimistic’ they will crack the case almost 14 years on

He told the newspaper: "Even if the public does not notice it much, our investigations in the Maddie case continue to run at full speed.

"We still assume the accused, Christian B, killed Madeleine. Even though the investigation of a case that will be 14 years old in a few days is very difficult after all this time, we remain optimistic and hopeful that we will be able to solve the crime.

"In doing so, we continue to work closely with the Metropolitan Police and the Portuguese law enforcement authorities, regardless of Brexit."

Mr Wolters said in June last year he believed Madeleine was dead and identified convicted paedophile Christian B as a prime suspect.

He is serving seven years for the rape of a 72-year-old woman in Praia da Luz — where two-year-old Madeleine vanished from her family’s holiday apartment on May 3, 2007.

She was in Portugal with her parents Gerry and Kate and her twin siblings.

A Danish-made documentary on Christian B will air in the suspect’s native Germany on April 28.

But a lawyer for Christian B has repeatedly called for police to show their evidence and vowed his client will never face trial over Madeleine.

Last month detective looking into the disappearance of Madeleine McCann want more cash to investigate German paedophile Christian B.

The operation has cost more than £12.5million since 2011 - but Met police chiefs have requested more funding in a bid to find vital evidence that could snare the man they believe is responsible for Madeleine's kidnap and murder.

Scotland Yard's special grant from the Home Office is set to expire this month, but bosses hope to be given further cash to continue probing Christian B for another year.

A summit between British, German and Portuguese detectives is due to be held in Lisbon in the next two months.