The prime suspect in the disappearance of Madeleine McCann may never be questioned by police as investigators say they do not have enough evidence and are just one witness away from justice.
Convicted paedophile Christian Brueckner, 43, was named by German police as a murder suspect, 13 years after Maddie disappeared while on holiday with her family in Portugal in 2007.
Having carried out searches and spoken to people close to Brueckner, the prosecutor leading the investigation has said police do not have enough evidence to secure an arrest warrant.
Maddie McCann disappeared after she left in her family's hotel room at a resort in Praia da Luz, Portugal, in 2007
Christian Brueckner was named as a suspect in Maddie's disappearance in June, but police now fear they do not have sufficient evidence to get a conviction
Hans Christian Wolters told the podcast They've Taken Her: 'At the moment our evidence is not so strong we are sure he will be sentenced by the court.
'Maybe we need one witness who can tell us the things we don't know.'
Last month Mr Wolters revealed they would not need to find Maddie's body in order to prosecute Brueckner of her murder.
When asked if he had any forensic evidence placing Brueckner inside the flat where Madeline was sleeping, Mr Wolters replied: 'I have an answer but we have decided not to divulge this information.
'I can't say 'yes' or 'no' as that would bring a thousand other questions and I cannot go into details.
'But you have to believe me when I say we have more evidence.
'Here in Germany our Public Ministry only divulges things when they are solid.'
Brueckner is serving time in prison in Germany after being convicted of drugs offences.
Prosecutor Hans Christian Wolters told a podcast: 'We need one witness who can tell us the things we don't know'
He has previously been convicted of possessing child abuse and of rape.
They told The Mirror: 'It feels like he is trying to lower expectations after coming out all guns blazing.'
Brueckner, who lived in the resort of Praia da Luz at the same time as Maddie's disappearance, has previously said he is innocent of any crime relating to the four-year-old.