McCann vanished while on holiday with her parents six years ago. The family from Leicestershire, England, was visiting Portugal when the 3-year-old went missing. Madeleine disappeared from her family's villa while her parents dined at a nearby restaurant in May 2007. Investigators will release two computer-generated sketches of a man who was spotted around the resort town of Praia Da Luz the day Madeleine went missing. Investigators also believe they have a better idea of when Madeleine may have been abducted.
Police announced in July that they have identified 38 "people of interest" in connection with the case.
British police said Sunday the timeline and version of events surrounding the disappearance of Madeleine McCann has "significantly changed," allowing them to build their most detailed reconstruction of the case yet.
London's Metropolitan Police said that investigators have been able to "place more significance" on events the night the then-3-year-old vanished from a Portuguese resort.
Det. Chief Inspector Andy Redwood says Scotland Yard's investigation has "significantly changed the timeline" and accepted version of events of that night. He did not elaborate on what has changed, but said he hopes when the public sees the new reconstruction, more information will come in that will move the investigation forward.
The reconstruction - and pictures of men police would like to speak to who were seen in and around the resort where Madeleine disappeared - will feature in a BBC "Crimewatch" program set to air Monday.
Police said they would like to identify the men and eliminate the innocent as suspects.
Since launching its own investigation, 41 people of interest have been identified by Metropolitan Police, including 15 U.K. nationals.
The Associated Press contributed to this report.