That would worry me. Whatever the theoretical security of those keys, they can be duplicated and one would assume a thief isn't likely to worry about posts here on EF stating that cutting e.g. Kaba keys in France is immoral.

Depending on how long the gap was between the key being stolen and it being returned, I'd consider changing the locks.

Yes, I have to say that it still really worries me...

And it does seem weird. Needless to say, I don't keep a spare key in my purse anymore.

My daughter's theory is that the perp. didn't want to get also stuck with stealing the key if he was caught, which I thought was astute, but then again she's my daughter . We witnessed 3 arrests that night on the way home. Apparently there had been a band operating that evening around the area (according to the police).

The purse was stolen 21:30, and found the next day around 09:00 - surely not possible to have a copy made (typical Swiss apartment key - i.e. copies not allowed) - or has anyone had experience of this?

Most of these security keys are coded so if a thief is found with a purse containing one it's a simple matter of the police looking up the code and connecting it with someone who had just reported a theft.

So your daughter probably got it right

And if it were me, I'd not bother changing the locks as the key was found so quickly.

Thanks a lot . Yes, the police noted the serial no. of my main key in their report...