It comes as Christian B continues to brag that the cops don’t have any evidence to link him to Maddie’s kidnapping and presumed death as well as five other sex crimes.
The convicted sex offender, 44, was first named as Maddie’s alleged kidnapper in a potentially significant UK and German police breakthrough in June last year.
But Christian B, who was recently transferred to a harsher prison dubbed “Alcatraz in Germany” for gruesome rape and drug-related offenses, has still not been questioned about Maddie 16 months later.
A McCann family source told The Sun Online, “The police aren’t telling us what’s going on, we’re in the dark because it’s an ongoing investigation.
“But if that’s him, and there’s no direct conclusive evidence, he might never say a word.” He doesn’t say a word now.
“He’s locked up for other crimes, so at least he’s in the best place – in jail.
“The Portuguese police had watched him before and last year they watched him again. We don’t know what it means, but without a confession we may never know.
“We don’t know what evidence the police have.
“Unfortunately, we may never know what happened to Madeleine. But we hope to find out. We remain hopeful after all these years.
When prosecutors named Christian B as a suspect, Kate and Gerry released a statement supporting the appeal but did not speak to him directly.
Three-year-old Maddie disappeared from a vacation apartment in Praia da Luz, Portugal in May 2007.
Her parents, famed cardiologist Gerry and ex-GP Kate, who has now returned to work full time as a doctor to help fight the coronavirus pandemic, cling to a silver lining that they might still be alive.
The couple, both 53, from Rothley, Leicestershire, have vowed to never give up on the search.
In May, Maddie – who is remembered around the world in one last iconic photo shortly before her fourth birthday – would have turned 18 and become an adult.
The family source recounted how Scotland Yard – under fire for failing to properly control Sarah Everard’s life-imprisoned cop killer Wayne Couzens – had been ‘brilliant’ in their investigation into Maddie, codenamed Operation Grange .
They said: “The Metropolitan Police have given us a lot of support, at times when their resources have been called upon, and for that we are very grateful. They were brilliant.
Maddie’s downsized team have been given nearly £ 350,000 in extra cash to spend trying to nail their prime suspect.
The Sun Online recently reported that the Home Office had approved a request for additional funding from the Met Police as part of their hugely expensive £ 12.5million investigation.
The boost comes after UK Chief Police Commissioner Dame Cressida Dick vowed her officers would continue the careful search “until there is nothing more to be done”.
She said: “We are working closely with the Portuguese authorities and the German authorities, and we will continue until there is nothing more to do.
“There is no funding problem at the moment. So far, we have received support whenever we felt that there was an avenue of inquiry to pursue to find out what happened to Madeleine. “
Ms Dick now faces calls for resignation in light of Sarah Everard’s police chaos.
Maddie’s prime suspect recently boasted that the cops didn’t have any evidence to link him to the missing girl case and five other sex crimes.
He is now in solitary confinement at Olenburg Prison, near Bremen, Germany.
But three forces – British, German and the original Portuguese lead investigator – have so far struggled to find vital evidence to trap him.
German prosecutor Hans Christian Wolters insisted: “We have gathered new evidence that adds to the case we are building against our prime suspect.
“I’m afraid I can’t say what it is, but it strengthens our work. This is not forensic but it is new circumstantial evidence that adds to the working theory that he is the responsible man. “
Over the summer, Christian B, jailed for raping an elderly American tourist in Portugal, spoke out for the first time since being named a suspect.
He wrote a letter calling the investigation “an unbelievable scandal”, proclaiming his innocence and urging prosecutors in charge of the case to drop.
He accused them of “shaming” the German justice system by making “scandalous” statements against it without laying charges.
In the astonishing explosion, he said that investigators should resign to “persecute an innocent person”.