German investigators' prime suspect in the disappearance of Madeleine McCann will be released from prison in a matter of weeks, local authorities have confirmed.

Christian Brückner, who is serving a sentence in northern Germany for a rape conviction, will be released by 17 September at the latest, the lead prosecutor investigating the toddler's disappearance told the BBC.

Hans Christian Wolters also said that he believed the 48-year-old German national was dangerous but that the current legal situation meant he must be released from prison without delay.

Brückner has never been charged with any crime in relation to Madeleine's disappearance and denies any involvement.

The then-three-year-old vanished from an apartment complex in Praia da Luz in the Algarve on 3 May 2007, sparking a Europe-wide investigation that has become one of the highest-profile missing persons cases.

Madeleine's parents had been dining with friends at a restaurant a short walk away while their daughter and her younger twin siblings were asleep in the ground-floor apartment. They had checked in on the children periodically until her mother, Kate, discovered she was missing at around 22:00 local time.

The case remains unsolved, but German prosecutors have pointed to evidence suggesting Brückner may have been in the area when Madeleine disappeared.

Mr. Wolters stated that research and evidence still support Brückner as the sole suspect, although they do not currently have enough to charge him formally.

Authorities suspect Brückner of murder in relation to Madeleine McCann, while British police continue to treat her disappearance as a missing persons case. Brückner has been assessed as a danger to society, leading to calls for restrictions upon his release.

Prosecutors are applying for conditions like ankle monitoring to be set upon his release. While Portuguese authorities initially led the investigation, it has since transitioned to the German prosecutors who have named Brückner a formal suspect.

Brückner has a lengthy criminal record, including previous convictions for child sexual abuse and is presently serving time for a rape committed in Portugal in 2005.