It is the missing child mystery that has remained unsolved for more than 18 years — the disappearance of British toddler Madeleine McCann.

The three-year-old vanished from her bed while on vacation with her family in the southern Portuguese resort town of Praia da Luz on May 3, 2007.

Since that day, she has never been seen, in a case that has received worldwide interest for years amid reports of sightings, books and television documentaries about her disappearance.

Almost two decades on, investigators in the United Kingdom, Portugal and Germany are still piecing together what happened on the night Madeleine went missing.

Images of Madeleine McCann were broadcast and distributed around the world in the immediate aftermath of her disappearance. (AFP)

On Monday local time, Portuguese police acting on behalf of a public prosecutor in Germany announced that fresh searches would be conducted.

So, what are they hoping to find and will any answers finally be reached? Here is what we know.

Searches will focus on Lagos and Praia da Luz

The country’s investigative Judicial Police (PJ) said in a statement that it was executing a European Investigation Order on behalf of the public prosecutor’s office in the German city of Braunschweig.

In 2022, that city identified German national Christian Brueckner as an official suspect in Madeleine’s disappearance.

Police in Portugal, as well as authorities in the UK and in Germany, have been searching for Madeleine McCann for more than 18 years. (AP: Armando Franca)

The PJ added that “a wide range of investigations, namely search warrants” would be carried out between June 2 and 6 in Portugal’s Municipality of Lagos and all evidence seized would be handed over to Germany’s Federal Criminal Police Office (BKA).

The search for traces of the child’s body will focus on an area between Praia da Luz and one of the houses where Brueckner lived when Madeleine disappeared, according to news reports by CNN Portugal and German newspaper Bild.

Braunschweig prosecutors told Reuters “criminal procedural measures” related to the McCann case were taking place in Portugal involving the BKA and Portuguese law enforcement, but did not provide further details.

Portuguese police, aided by German and British officers, last searched an area the Arade dam near Silves in the country’s south in 2023. (AP: Joao Matos)

Who is the main suspect in Madeleine McCann’s disappearance?

Christian Brueckner is currently serving a seven-year prison sentence in Germany for raping a 72-year-old female US tourist in Praia da Luz in 2005.

He has been formally identified as a suspect in the McCann case and is under investigation on suspicion of her murder, but has never been charged.

In October 2024, he was acquitted by a German court of unrelated sexual abuse charges relating to two children between 2000 and 2017.

Prosecutors in that case had called for him to be jailed for a further 15 years, describing him as a “dangerous psychopathic sadist”.

He spent many years in Portugal, including in Praia da Luz, around the time of Madeleine’s disappearance. Brueckner has denied any involvement in her disappearance.

What is known about how Madeleine McCann went missing?

The image of the blonde-haired, hazel-eyed Madeleine McCann, with a distinctive smudge extending from her iris — a congenital defect known as a coloboma — was once shared endlessly around the world as part of the global search to uncover her whereabouts.

The tourist beach town of Praia da Luz outside of Lagos in Portugal’s south is the last location Madeleine McCann was seen. (Reuters: Hugo Correia)

In the week before she vanished, the toddler’s family had embarked on a holiday to the Portuguese Algarve coast with friends.

On the night of May 3, 2007, the couples gathered at the Praia da Luz resort where their three kids slept. They took turns checking on their children.

At 9:05pm, Madeleine’s father Gerry McCann took his turn to do the rounds. He found all three of his children, Madeleine and her twin siblings Amelie and Sean McCann, asleep in their beds.

Fifty-five minutes later at 10pm, Madeleine;’s mother Kate McCann went to do her check. The twins were still in bed, but Madeleine’s bed was empty apart from a blanket and cuddly toy.

In the immediate moments of panic after that discovery, the search began to find Madeleine.

In the 18 years since, multiple searches and major, multi-million-dollar police operations have been tasked with finding answers — all, thus far, to no avail.

Local police in an early investigation of Madeleine’s whereabouts concluded that she had likely been kidnapped, and there were suspicions that she may have fallen victim to human traffickers.

To this day, no major leads have been produced that could detail the exact nature of what happened that night.

Madeleine’s parents, Kate and Gerry McCann, embarked on an expansive media campaign in the aftermath of her disappearance. (AP: Sang Tan, file)

How many searches for Madeleine have there been?

The last time police resumed searches in the case was in 2023, when detectives from the three countries took part in an operation searching near a dam and a reservoir about 50 kilometres from the Praia da Luz resort.

During that operation, unspecified soil samples from the reservoir were examined before being handed over to German authorities.

At the time, Portuguese police did not say whether any useful clues were found by sniffer dogs and investigators using equipment like tractor-based tree cutters in various areas.

Before then, it was in 2020 that German police declared they were zeroing in on Brueckner as the likely culprit behind Madeleine’s disappearance. Portuguese prosecutors then also identified the German man as a formal suspect.

A phone linked to him in 2007 placed him in the area where Madeleine went missing within a 30-minute window.

Prior to 2020, former British prime minister David Cameron had asked in 2011 for an “independent, transparent and comprehensive” review of all information relating to the girl’s disappearance.

In 2013, Scotland Yard revealed it had “new evidence and new witnesses” in the case and was opening a formal investigation into the girl’s disappearance. That only resulted in what police described as a “new understanding of events” on the night Madeleine went missing.

The United Kingdom’s Scotland Yard has received tens of millions of dollars in government funding for its Operation Grange investigation into Madeleine’s disappearance. (Suzanne Plunkett: Reuters)

The only other search that has occurred was in 2007 in the aftermath of the toddler’s disappearance, in an investigation that faced significant challenges due to the tensions and differences in investigative methods used by Portuguese and British detectives.

After the news of the latest search to take place this week in Portugal, London’s Metropolitan Police said they were aware of the renewed operation carried out by the BKA in Portugal, adding the force was not present there but would “support our international colleagues where necessary.”

On May 3, Gerry and Kate McCann released a statement on behalf of their family to mark the 18th anniversary of Madeleine’s disappearance.

“The years appear to be passing even more quickly and whilst we have no significant news to share, our determination to ‘leave no stone unturned’ is unwavering,” the statement said.

“We will do our utmost to achieve this.

“May is also Madeleine’s birthday — her 22nd this year. No matter how near or far she is, she continues to be right here with us, every day, but especially on her special day.

“We continue to ‘celebrate’ her as the very beautiful and unique person she is. We miss her.”