A former chief superintendent at Scotland Yard said the force should have been "brought in from the outset" to deal with the Madeleine McCann disappearance.
It comes as the head of the new full-scale Metropolitan Police inquiry into the Leicestershire child's disappearance has said there are 38 persons of interest, including 12 British nationals, that they want to speak to.
Mr Davies said: "The lesson surely has to be that you involve professional police forces who have the experience and ability in a global scenario in terms of kinap and ransom.
"Scotland Yard are arguably one of the best in the world, they should have been brought in from the outset as I did call for."
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.
What happened to Madeleine? It is likely only one person knows the answer, and finding that person is the focus of a British investigation.