The Met Police has announced that the review into Madeleine McCann's disappearance has now become an investigation with 38 people, including 12 UK nationals, identified as "persons of interest".
Police believe Madeleine could still be alive, and they have drawn up a list of 38 people - 12 of them British - who they want to speak to.
What happened to Madeleine? It is likely only one person knows the answer, and finding that person is the focus of a British investigation.
The Met Police said there are 38 people of interest in the Madeleine McCann case. Here is a timeline of the key events in her disappearance.