The detective made it clear that they were looking at a "criminal act by a stranger", most likely a planned abduction or a burglary that Madeleine had disturbed. There had been a fourfold increase in local burglaries between January and May 2007, including two in the McCanns' block in the 17 days before the disappearance, during which intruders had entered through windows. In an interview in April 2017, just before the 10th anniversary of the disappearance, Scotland Yard's Assistant Commissioner, Mark Rowley, appeared to dismiss the "burglary gone wrong" hypothesis, while adding that it was "not entirely ruled out". Referring to the suspects who might have been involved in burglaries in the area, he said that police had "pretty much closed off that group of people". The remaining detectives were focusing on a small number of inquiries that they believed were significant. Also that month there were claims that Scotland Yard was looking for a woman seen near 5A at the time of the disappearance.
The detective said in 2013 that, "on one reading of the evidence", the disappearance did look like a pre-planned abduction, which "undoubtedly would have involved reconnaissance". Several witnesses described men hanging around near apartment 5A in the days before the disappearance and on the day itself. In May 2013 Scotland Yard wanted to trace 12 manual workers who were at the Ocean Club when Madeleine disappeared, including six British cleaners in a white van who were offering their services to British expats. In October 2013 Scotland Yard and the BBC's Crimewatch staged a reconstruction—broadcast in the UK, the Netherlands and Germany—during which they released e-fits of the men seen near 5A and of the Smith sighting. Days after Crimewatch aired, Portugal's attorney general reopened the Portuguese inquiry, citing new evidence.
Another theory is that Madeleine, nearly four at the time, left the apartment by herself, perhaps to look for her parents, and was abducted by a passer-by or fell into one of the open construction sites nearby. This is widely regarded as unlikely. According to her mother, Madeleine would have had to open the unlocked patio doors, close the curtains behind her, close the door again, open and close the child gate at the top of the stairs, then open and close the gate leading to the street.