The disappearance of Madeleine McCann is one of the most mysterious and tragic missing persons cases the world has ever seen.
The three-year-old disappeared on May 3, 2007 from her bed in her parent's holiday villa in Portugal, while the couple were having dinner with friends at a nearby tapas restaurant.
Maddie has never been found - dead or alive - and no tangible leads have ever been discovered. If she is alive, she would be 17 years old today.
Now 13 years later, the case is back in the spotlight as British and German authorities are investigating a new suspect, a 43-year-old German man, who has previously been convicted over the sexual abuse of children.
The suspect is currently serving a "long" prison sentence "for an unrelated matter", German officials said in June. This suspect is now being investigated for the "possible murder" of Maddie McCann.
Last year, the case also faced renewed interest following the release of the Netflix documentary, The Disappearance of Madeleine McCann.
The documentary once again turned the focus back onto the McCann family, who live in Rothley, a small English town in Leicestershire, about 2.5 hours north of London.
Maddie's parents Kate and Gerry McCann, both 52, have two other children, twins Sean and Amelie, both 15.
While Maddie's face is instantly recognisable around the world, we know very little about the two siblings she was sleeping just metres away from when she was allegedly stolen from her bed.
The twins were aged only two at the time of their sister's disappearance.
The three siblings were all sleeping in the same bedroom, while their parents dined at their hotel's restaurant just 55 metres away.
When Kate McCann went to check on her children at 10pm, she found Maddie had disappeared from her bed, while her twins were sleeping peacefully, untouched.
So what has life been like for Sean and Amelie, growing up without their older sister?
Here's everything you need to know.
There are no publicly-available photos of Sean and Amelie, who are now both 15 years old.
They keep a very low profile and are never photographed by the press, despite their parents leading a very public awareness campaign, involving the media and police, in an attempt to find Maddie.
The twins attend a local Catholic high school in their small town, which has retained a place for Maddie, who would be 17 years old now, if she is ever found.
Both Sean and Amelie are both aspiring athletes, competing in swimming championships, triathlons and cross country racing.
The absence of their sister has left a dark cloud over the lives of Sean and Amelie, despite their parents trying to create the most normal life for them as possible.
In an interview with The Sun, Kate McCann said her twins have "grown up essentially without Madeleine but knowing their sister is missing and they want her back."
Keeping busy is the family's way of coping, but still it will never fill the void left by Maddie's absence.
"They have their own friends and they keep busy and they're really sporty but their only wish is for their big sister to come home. We miss our complete family of five," an anguished Kate told The Sun.
"As a family 98 percent of the time we're busy. I don't know if that's a conscious thing but it helps. The urge to look for Madeleine absolutely hasn't changed at all."
Sean and Amelie's 13th birthday celebrations in 2017 were particularly poignant, as they were held around the 10 year anniversary of Maddie's disappearance.
While the twins celebrated the special milestone with friends and family, all they really wanted for their birthday was for Maddie to be found.
"Their only wish is for their big sister to come home," a family friend told The Sun.
Kate and Gerry threw a joint birthday party for the twins to celebrate the duo officially becoming teenagers.
Guests at the celebration revealed the party was filled with reminders of Maddie.
One guest said: "There will be prayers to remember Madeleine as well wherever she is. Kate and Gerry want to give the twins a memorable occasion, they're teenagers now and that's a big deal.
"But the party will be marred with a tinge of sadness because Madeleine is not here to join in the fun."
Maddie's parents say despite the immense tragedy their family has faced, they try to live their lives in "as normal way as possible", for the sake of the twins.
Heartbreakingly, Kate has previously revealed she still buys birthday and Christmas presents for Madeleine. They are all ready and waiting in her room in the family home, which has been left untouched since her disappearance.
"I obviously have to think about what age she is and something that, whenever we find her, will still be appropriate, so there's a lot of thought goes into it," she told the BBC.
"But I couldn't not, you know; she's still our daughter, she'll always be our daughter."
Watch the trailer for the Netflix documentary below. Story continues after the video
Kate says despite all of her children being so young when tragedy struck, Amelie and Sean still remember Maddie and talk about her often.
"The twins are doing really well," Kate told The Sun in 2015.
"They are up to date, they know everything, they know if we are meeting police. There is nothing kept from them.
"They've grown up essentially without Madeleine, knowing their sister is missing and they want her back.