“In connection with the disappearance of the then three-year-old British girl Madeleine Beth McCann…, the Braunschweig public prosecutor's office is investigating a 43-year-old German citizen on suspicion of murder,” said federal police in a statement.

On May 3rd, 2007, a few days before her fourth birthday, “Maddie” disappeared from her family's holiday apartment in the Algarve village in Portugal as her parents dined with friends at a nearby restaurant, sparking one of the biggest searches of its kind in recent years.

Despite a wide range of suspects and theories about what happened, no one has ever been convicted over her disappearance.

The suspect, who was not named by police, is serving a “long prison sentence”, and has previous convictions over child sexual abuse, said Germany's federal criminal agency.

The man was initially convicted of drug trafficking and in 2019 for raping a senior citizen in Portugal. The convictions took place in Braunschweig, Lower Saxony, reported Spiegel Online.

Lead investigator Christian Hoppe told ZDF television that their investigation had led police to suspect that the man was involved in the killing of Madeleine.

He regularly lived between 1995 and 2007 in Algarve, police added, launching an appeal for information relating to two vehicles that the suspect was known to have used as well as two phone numbers.

German police photo shows a Volkswagen T3 Westfalia with a Portuguese plate. Photo: DPA

The first is a dark coloured Jaguar XJR 6 which bore a German plate from the city of Augsburg. The second vehicle is a Volkswagen T3 Westfalia with a Portuguese plate.

Portuguese police closed their investigation in 2008 after 14 months, which at one point implicated her parents in her abduction before their names were cleared.

British police opened their own inquiry in July 2013, but excavations in Praia da Luz yielded no evidence.

They have classified the case as a “missing persons” inquiry due to a lack of evidence if Madeline is alive or not, reported the BBC on Thursday. Yet it has been classified by German investigators as a murder inquiry.