Why didn't the Spanish police pick this up??

*Spoilers!*

I thought this was a bit strange. Frederic calls from the payphone to the police saying he is a tourist that found this child. He says the child has no ID or any documents on him.
But how could the tourist, if he was real, have known this, giving the circumstances of this kid?
He is sitting in a phonebooth, not receptive to any kind of contact with other people, scared and freaked out (it's an act, but the police nor the fake tourist would know that), he covers his face, is kneeling, has his arms around his legs. He completely shuts himself off.
How could the tourist have known what the kid was carrying, for example as ID or anything else?

If the police would have asked themselves that question, it might have come to light that there was no tourist and that Frederic made the call himself. That would have uncovered him from the start i guess .....

Also, why didn't the police ever consider tracking the tourists down? Didn't they find it a bit strange that the tourists would have left the kid there before the police came to never hear from them again? They could have had vital information helping the police with the investigation about who Frederic was ...

I think a real miss from the police!