Police investigating the disappearance of Madeleine McCann 16 years ago have brought an end to the three-day search of a Portuguese reservoir that is thought to have resulted in the discovery of a "relevant clue".

The German-led investigation began on Tuesday after they requested access to the Barragem do Arade reservoir, with teams using diggers and divers to carry out the search.

According to Portuguese newspaper Correio da Manha, a clue was found during digging after teams focused on a specific area of the reservoir - with sources saying pieces of clothing and plastic were among items found on the site that are set to be sent for forensic analysis.

However, the McCann family may face a wait of months before the results of the analysis return, according to The Mirror, which reported that evidence had been sent to Germany in a process that may not yield results for many weeks.

German authorities have not revealed why they have begun searching the site, but it is believed to have been visited by suspect Christian Brueckner, who is serving time in prison in Germany due to unrelated crimes.

However, it is believed authorities were searching for a videocamera belonging to Brueckner that they believe may contain important photographic evidence.

Portuguese police were told on Thursday they would no longer be needed to help monitor the roads in the region past 4pm, as the search came to an end after three days.

• Madeleine McCann reservoir search ends in Portugal (Sky News, 2 mins)

Where were police looking?

On Tuesday, search teams were seen scouring the banks – hammering away at the ground with pickaxes and combing through small rocks with rakes and spades.

Throughout Wednesday and Thursday, police focused on an area of woodland on the peninsula.

Officers used shovels to excavate their area of focus, and sniffer dogs and pickaxes have also been deployed over the course of the searches.

As some concentrated on the digging site, others used rakes and shovels to scour the surrounding area, slowly making their way through the recently trimmed undergrowth.

Divers have also been spotted investigating the water.

The woodland showed pathways had been cut by heavy machinery, leading to the main, flattened 160 square foot excavation area. Holes dug by police had been left around 2ft deep.

The concentrated search area was also flattened with eight small holes dug with shovels.

• Police looking for Madeleine McCann ‘to begin search of remote reservoir in Portugal’ (Evening Standard, 5 mins)

Why did police begin the search?

German authorities have not revealed why they have requested access to the site, only to say it is in relation to the McCann case.

The prosecutor for the city of Braunschweig, Christian Wolters, said they were acting on the basis of "certain tips".

Authorities in Braunschweig were the ones to identify Brueckner as a suspect in the case in 2020.

Wolters told German public broadcaster NDR the new information had not come from the suspect and they did not have a confession or "any indication from the suspect of where it would make sense to search."

The Sun reported that investigators previously found photos and video of Brueckner at the reservoir. Citing a source close to the investigation, the MailOnline has reported that police were looking for a gun and a camcorder belonging to Brueckner. Neither report has been confirmed by investigators.

What is the latest on the Madeleine McCann case?

Convicted paedophile Brueckner, 45, remains the prime suspect in the McCann case, but he has yet to face any charges and denies involvement.

The German national is currently serving a seven-year sentence for raping a 72-year-old US woman in 2005 in the Algarve – the same region of Portugal from where McCann disappeared.

In 2020 German police named a man they thought was "probably" responsible for the girl's abduction and murder – describing him only as "Christian B" due to the country's strict privacy laws.

He was then declared an official suspect by Portuguese police in April 2022, with subsequent reports suggesting authorities in Germany were poised to charge him.

In 2005, he raped a 72-year-old US widow at her home in Praia da Luz, which he is currently serving a prison sentence for.

Brueckner was convicted in 2017 of sexually abusing a child and "creating and possessing child pornographic material" in Germany and sentenced to 15 months in jail.

This week's search was the first major operation of its kind since June 2014 when British police were given permission to do digs in Praia da Luz that involved sniffer dogs trained in detecting bodies and ground-penetrating radar.

The reservoir being searched is near Silves where a lorry driver says he saw a woman handing a child-like Madeleine McCann over to a man two days after she went missing from her Praia da Luz holiday apartment on 3 May 2007.

It was searched twice in February and March 2008 by divers hired by a Portuguese lawyer.

Madeleine was just three years old when she vanished, and her disappearance has remained a high-profile case throughout, with detectives from the UK, Portugal and Germany trying to find the person responsible or her abduction.

• Sex offences trial of Madeleine McCann suspect cancelled in Germany (The Guardian, 2 mins)

What else do we know about Christian Brueckner?

Born in Germany in 1976, Brueckner was 17 when he was convicted of molesting a six-year-old girl in a playground in his hometown of Wuerzburg, Bavaria, in 1994.

The following year, after he'd turned 18 and got his driving licence, he moved to the Algarve with his then-girlfriend in 1995, escaping a youth custody sentence and abandoning a car mechanic apprenticeship.

Brueckner, whose relationship soon ended, took on a variety of odd jobs at the Portuguese resort.

He was convicted in 2017 of sexually abusing a child and "creating and possessing child pornographic material" in Germany and sentenced to 15 months in jail.

In December 2019, he was sentenced to seven years in prison for the rape of an American woman. He is also being investigated for the rape of an Irish tour rep in 2004.

However, the serial sex offender, who is in his mid-40s, is yet to face any charges related to the McCann case so far due to a lack of sufficient evidence.

In April this year, five unrelated charges of rape and sexual assault against Brueckner were thrown out by a German court because he lived in a different region of the country at the time of the alleged offences.

The court’s decision means legal authorities in Braunschweig have no jurisdiction over Madeleine’s case.

• Who is Christian Brueckner? (The Independent, 4 min read)