STORY: On Tuesday, Portuguese and German authorities began searching a reservoir near the area where a British three-year-old, Madeleine McCann, went missing in 2007.
Jim Gamble, a former detective who played a central role in the investigation, said the search gives reason to be hopeful.
"I think it is reasonable to be hopeful two-fold. One is that the German police are continuing at pace, they are not taking off the pressure, they are continuing to invest resource. And number two, at some stage there's got to be a breakthrough in this case.''
The move is the most recent development in the search for the girl, whose disappearance, 16 years ago, continues to trigger huge media attention even now.
So, who is Madeleine McCann and what happened to her?
On May 3, 2007, Madeleine McCann vanished from her bedroom in the apartment her family were staying in at the Praia da Luz resort in Portugal, while her parents were out dining.
Her twin baby siblings were also home and asleep.
The family turned to the media for help, believing local police acted too slowly and had failed to secure the crime scene.
Madeleine's mother Kate McCann.
"What we really do want is ask the Portuguese people, we need to ask them please help us there is a little girl still missing"
There have been many twists and turns in the case over the years across multiple countries, including libel lawsuits against tabloids that suggested the parents were involved with the disappearance.
But in June 2020, British and German police said they had identified a new suspect, a 43-year-old German man.
Hans Christian Wolters is Braunschweig State Prosecutor.
"The public prosecutor's office in Braunschweig is investigating a 43-year-old German national on suspicion of murder in connection with the disappearance of three-year-old Madeleine Beth McCann on May 3, 2007"
Who is Christian Brueckner?
The suspect, Christian Brueckner, lived in the Algarve between 1995 and 2007 and burgled hotels and vacation apartments as well as trading drugs.
He had been jailed for seven years in 2019 for raping and robbing a 72-year-old American woman in her home there.
In April 2022, he was formally identified by Portuguese police as an official suspect in Madeleine's disappearance.
He has denied any involvement and has not been charged with any crime related to it.