Vital forensic clues may have been destroyed in the hours after Madeleine McCann's disappearance, a leading Portuguese policeman has said.
Mr de Sousa said the forensic team's work had been complicated.
Chief Inspector Olegario de Sousa said so many people entered her room looking for her after she disappeared that forensic teams faced a difficult task.
Mr de Sousa told a Portuguese paper 20 people entered the three-year-old's room the night she disappeared.
Madeleine was taken from the Algarve resort of Praia da Luz on 3 May.
Mr de Sousa said that among those who entered the room on the night she disappeared were parents Kate and Gerry McCann, other holidaymakers and friends and staff from the Ocean Club resort.
He told the Diario de Noticias newspaper: "The presence of so many people - especially in the room where the little girl slept with her brother and sister - could have at least complicated the work of the forensic team.
"At the very worst they would have destroyed all the evidence. This could prove to be fatal for the investigation."
It is thought Madeleine was snatched from the family's apartment at the Praia da Luz resort while her parents were at a nearby restaurant.
Samples from Madeleine's bedroom at the resort have been sent to three Portuguese forensic labs in Lisbon, Porto and Coimbra, all part of the country's Instituto Nacional de Medicina Legal (INML).
On 1 June the lab reported it had found traces of a "stranger" amid the DNA material gathered.
A source close to the family told the Press Association: "It's insensitive at the very least. Of course the family are going to search the apartment.
Madeleine McCann went missing while her parents were at a restaurant
"If your child goes missing, you search under the beds, in the wardrobes, behind the doors, everywhere.
"It's inevitable that there were people in the bedroom. Even if what the police are saying is true, it's very unhelpful to say it publicly."
On the 45th day since her disappearance, Madeleine's parents attended a two-hour church ceremony in Praia da Luz.
"I can't think about last year and how we spent it, I honestly can't," Mr McCann, 39, said.
"I can't really think about anything else, other than how we can help try and get Madeleine back."
On Friday, the McCanns are due to set aloft 50 balloons from 50 countries to highlight the fact Madeleine will have been missing for 50 days.