The McCann family has welcomed the Metropolitan Police's shift from a review to an investigation into missing Madeleine.
It is clearly a big step forward in establishing what happened and, hopefully, towards bringing whoever is responsible for Madeleine's abduction to justice.
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.