Filmmakers drew on new interviews with more than 40 contributors, 120 hours of interviews, archival news footage, and reenactments to put together the series.
McCann was aged three when she vanished during a family holiday in Praia da Luz on the Algarve in Portugal in May 2007.
The claim will be made in a bombshell new Netflix documentary to be released this week.
McCann disappeared on May 3, 2007, from the apartment where she was sleeping with her two-year-old twin siblings.
Netflix To Release Madeleine Mc Cann Documentary Later This Month
The documentary also hears from private investigator Julian Peribanez, who was hired by the McCann family, and former Portuguese police chief Goncalo Amaral.
A Netflix documentary about the disappearance of Madeleine McCann will feature interviews with Jim Gamble QPM, from Bangor, Co Down, one of the UK's most experienced and outspoken experts on the safeguarding of children online. Year on year other techniques, including facial recognition, are getting better.
The McCanns previously released a statement distancing themselves from the series.
"We did not see and still do not see how this programme will help the search for Madeleine and, particularly given there is an active police investigation, could potentially hinder it". "Consequently, our views and preferences are not reflected in the program".
A source inside the production team added: "We would have welcomed the opportunity of working with the McCanns directly but they informed us they couldn't and wouldn't consider taking part while a police investigation is into their daughter's abduction is ongoing".
Watch The Disappearance of Madeleine McCannon Netflix from Friday 15 March.