Detectives have key questions for witnesses to the disappearance of Madeleine McCann

The Scotland Yard officers have analysed minutely events which happened just before, during and immediately after Madeleine vanished on May 3, 2007 and appear to be seeking new information and clarification from important witnesses.

Among those scheduled for requestioning is Silvia Batista, who ran the service and maintenance departments of the Ocean Club at Praia da Luz on the Algarve where the McCanns were staying.

Shortly after the alarm was raised, Mrs Batista was contacted at her home in nearby Lagos and immediately went back to work.

When she arrived at a reception area she saw Madeleine's father Gerry on his knees on the floor crying out for help and banging his hands on the floor.

A few minutues later she entered the bedroom at apartment 5a and said that the shutters were down, the windows closed and the curtains slightly open.

Kate McCann has said that when she arrived to find Madeleine gone, the shutters were partly open in the bedroom, leading her to believe that Madeleine had been taken through the window.

In her statement Mrs Batista said Gerry told her he had closed the windows as their other two children, Sean and Amelie, then 18 months, were still asleep in separate cots in the bedroom.

Mrs Batista, a former receptionist at the Ocean Club, worked closely with her husband Joao, who was head of maintenance and services.

In the past year both were made redundant because of falling bookings at the Ocean Club, which have been blamed on the recession and publicity surrounding Madeleine's disappearance.

Another facing requestioning is John Hill, manager of the Ocean Club.

When he arrived at the club after receiving a call at 10.28pm from a colleague, some 100 people were already searching for Madeleine.

He also spoke with Kate and Gerry that night in their apartment and helped arrange for photos of the child to be distributed.

Mr Hill and his wife Donna printed pictures after being given a memory stick by Russell O'Brien, a friend of the McCanns whose partner Jane Tanner's picture of Madeleine gathering tennis balls is well known. 

Donna Hill is likely to be requestioned early in the New Year.

Scotland Yard detectives are also interested in claims that a set of keys to apartment 5a, kept in the maintenance section, went missing in the week that Madeleine vanished, first revealed by the Sunday Express last February when we reported that a former maintenance worker said the disappearance of the keys had not been reported to the authorities.

Detectives also want their Portuguese counterparts to interview Mario Fernando, 47, who came forward last May to say he saw a suspicious man wearing sun glasses in a stairwell looking at apartment 5a 24 hours before Madeleine disappeared. The former Ocean Club laundryman was collecting sheets when he saw the man: "I saw the weird guy and we nearly bumped into each other.

"He was embarrassed. He was nervous. He was walking out from the hole under the stairs and must have been much further inside but had taken several steps back after hearing me coming.

"He had a really fat face and had two-tone sunglasses on."

Last week it was revealed that Robert Murat was one of those on the Yard's list of people it wants more information from.

Mr Murat told the Sunday Express he would be happy to cooperate but has not received anything official yet from the authorities.

Portuguese police have to conduct the interviews but Scotland Yard officers can sit in during questioning. Some interviews were due to be held last week but they now look likely to be held in the New Year.

Former Scotland Yard murder detective Peter Bleksley said that this next stage of the investigation was a "logical progression" for the police.

"I would think that they have been concentrating on the timeline in the review period and they have may have come across some inconsistencies which they want to look into," he said. "That would be my thinking on this.

"They will want to know who was where, who saw what and at what time and try to work through the inconsistencies while at the same time seeking new information.

"Going back to square one will have formed a big part of the original review which has now moved into the investigative stage. It is a logical progression."