The answer to that lies with the Amaral investigation initially and as we know no stone was left unturned when it came to investigating the McCanns and their friends.
Do you think they would have failed to carry out all investigative measures? ... starting with ... the timeline.
It seems you have taken us off topic Brietta, by moving the debate from an examination of the timeline to a discussion about innocence and investigations, As far as I know not one investigation has made any meaningful attempt to verify the timeline. Some of the questions which should have been asked;
The chef left the central kitchen near the Millenium at around 21,10 and returned around 21.40. His colleagues were not questioned to check these times.
He parked his car at the Tapas and noticed another car there. Stephen Carpenter saw these cars, Russell O'Brien, when asked, saw no parked cars at 9.30pm.
The waiters and cooks were never questioned about the average serving times for the meals. Fiona said the food came quickly that night. She and her mother also said initially that they were all there at 9.45. Even if she arrived at 9pm was it really fast for the starters to arrive at 9.20?
The receptionist was never questioned about Matt's visit to reception with regard to calling the police.