The PJ took the McCanns fingerprints the very night Madeleine disappeared?

[John]

I found this very odd indeed.  The PJ took Kate and Gerry's fingerprints the very night that Madeleine disappeared.  From Kate's book...

Now one of the PJ men (I remember him very distinctly: he was quite young and, I assumed, probably quite junior) entered the room, where the twins were stil asleep, with a brush and a pair of latex gloves. He also tried to take fingerprints from Gerry and me. Unsuccessfuly, as it turned out: we had to provide them again the next day at the police station.

Why was the PJ taking fingerprints from the parents of a lost child before the circumstances of her disappearance had even been established.  It wasn't as if they had anything to check them against at that stage unless...

[Miro]

Personally I would have expected the fingerprints and full contact details to be taken of everyone who had entered the apartment or been close to it.

This would allow their prints to be considered with any found during the crime scene examination..............

[Cariad]

Personally I would have expected the fingerprints and full contact details to be taken of everyone who had entered the apartment or been close to it.

This would allow their prints to be considered with any found during the crime scene examination..............

Seconded. They needed to eliminate fingerprints that were expected to be there. They started brushing for prints that night, then resumed the next day when it was light.

[icabodcrane]

We had a break in whilst on holiday once  ...  they broke the porch window

When the police came they did the 'dusting thing'  and took all our prints  ...  to eliminate us from any prints found I suppose   

The McCanns had told the police that the window and shutters had been found opened, so I  guess the same logic applied