The prime suspect in the high-profile case of Madeleine McCann's disappearance has declined to be interviewed by the Metropolitan Police, the force has said.
The Met stated that an international letter of request was sent to Christian Brückner ahead of his impending release for a separate offense, which he later rejected.
German national Brückner, 48, has never been charged with any crime related to the McCann case and denies any involvement.
Madeleine vanished in the Portuguese resort of Praia da Luz in 2007. She and her siblings had been left sleeping in a holiday apartment while her parents, Kate and Gerry, went for dinner at a nearby restaurant.
They checked in on the children periodically until Kate discovered Madeleine was missing at around 22:00.
Brückner is currently serving a seven-year prison sentence in Germany for the rape of a 72-year-old woman at her home in Praia da Luz in 2005.
German authorities have indicated that he will be released soon.
Detective Chief Inspector Mark Cranwell stated that Brückner remains a suspect in the Met's ongoing investigation into Madeleine's disappearance. He has been the primary suspect in the German and Portuguese investigations since 2020 and 2022, respectively.
We have requested an interview with this German suspect, but for legal reasons, this can only be done via an International Letter of Request which has been submitted, noted Det Ch Insp Cranwell.
Despite Brückner refusing the interview, he expressed that the investigation will continue to pursue any viable lines of inquiry.
We can provide no further information while the investigation is ongoing, he added.
Madeleine's disappearance has become one of the highest-profile unsolved missing person cases globally.
German prosecutors have pointed to evidence, including mobile phone data, indicating that Brückner may have been in the area when she disappeared, consistently asserting that they believe he is responsible. However, there hasn't been sufficient evidence to bring charges against him.
Brückner, who spent many years in the Algarve, has a history as a petty criminal and a convicted sex offender, with previous convictions including instances of sexually abusing children.
Search operations by police between the locations connected to the McCanns and Brückner in June yielded no breakthroughs.
In 2023, authorities conducted searches near the Barragem do Arade reservoir, about 30 miles from Praia da Luz, where Brückner spent time.
Due to the differences in legal systems, German officials suspect Brückner of murder in connection to Madeleine's case, while British police treat her disappearance as a missing persons case.
The funding for the Met's investigation, Operation Grange, has surpassed £13.2 million since its inception, with an additional £108,000 granted by the government in April.