MISSING: Madeleine McCann

The kidnapper of Madeleine McCann drugged her and her twin brother and sister so they would all be quiet while she was snatched.

A duplicate key may also have been used to gain entrance to the holiday apartment where the children were sleeping, say investigators.

It means the monster is still a threat to children living or holidaying on Portugal’s Algarve and must be caught urgently as he is highly likely to reoffend.

Former police detectives David Edgar and Arthur Cowley have spent months re-analysing every shred of evidence.

They are convinced the ­abductor went to the family’s apartment on May 3 2007 fully prepared with sufficient drugs, probably ­chloroform, to knock out all three children.

The fact that Sean and Amelie, then just 18 months old, failed to wake when the alarm was raised, nor even as they were taken to another apartment in the cold night air, has persuaded the detectives that they, too, must have been drugged.

Had the twins been tested for drugs immediately, any ­medication used could have been established, making it easier to identify the kidnapper, but vital time was lost.

Chloroform can be made ­easily and other sedatives, such as the horse tranquilliser ketamine, are commonly in circulation in the criminal underworld.

Even now, however, experts say there may be forensic clues on clothing or bedding which could yield a breakthrough.

The Sunday Express can further reveal that the McCanns’ private detectives are working on a solid theory about exactly how Madeleine was abducted. 

Just as television investigator Donal MacIntyre suggested in this paper three weeks ago, they believe there was a dry run prior to the kidnap that fateful night at apartment 5a of the Ocean Club resort in Praia da Luz.

While checking the layout of the apartment the night before, the kidnapper probably woke Sean, who in turn woke Madeleine. In the morning she had told Kate and Gerry she was frightened.

The fact that the children woke up is thought to have persuaded the kidnapper to use knock-out drugs when he returned the next night to take Madeleine, three.

On the question of the duplicate key, holidaymakers often left front door keys under the doormats during the day.
A theory emerging is that the kidnapper had a duplicate key to apartment 5a, which could have been used on the night to enter by the front door.

Mr Edgar and Mr Cowley do not believe Madeleine was taken through an open window as it would have been awkward, time consuming and there were no forensic clues left behind.

It is far more likely, they say, that he simply walked out of the front door with her in his arms. It had been thought that the front door was double locked, making it impossible to open from the inside, but this doubt falls away if there was a duplicate key.

The theory suggests the ­kidnapper had been targeting the apartment for a long time and had a detailed knowledge of the lock system.

With the front door unlocked, it is easy to simply pull a latch across to open it from the inside.

Another possibility is that the front door was not double-locked when Kate and Gerry left through the unlocked patio doors to join their seven friends at the resort’s tapas bar some 30 metres from their apartment.

Meanwhile it emerged yesterday that the parents of a two-year-old girl who has gone missing in New Zealand are being ­supported by the ­McCanns.

Aisling Symes vanished from a relative’s house in an Auckland suburb on Monday.

Her mother Angela had been close by, standing beside a washing machine.

There have been reports that the girl was later seen with a woman of Asian appearance.

Detectives believe she was ­abducted. Despite repeated ­appeals for help their searches have so far drawn a blank.
Kate and Gerry McCann said their “thoughts and prayers” were with the family.

The little girl’s father, Allan Symes, who is originally from County Waterford in Ireland, made an emotional plea for her return, saying: “These recent days have proven to be the most harrowing of our lives; no sleep and we feel like we’re barely ­existing, just surviving every ­moment, not knowing where ­Aisling is.”

It has also emerged that police in Sweden are trying to find a girl said to bear a resemblance to Madeleine after a photograph was posted on a website.

However, she does not appear to have the distinctive mark Madeleine has in her right eye.