GringoPost | Cuenca, Ecuador: Police knocking on hotel room door

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Police knocking on hotel room door

2 policemen have knocked on my (and others) Cuenca hotel room door on 4 occasions checking my passport to be sure I was in the country legally. I was hesitant to open the door as anyone can knock and say they are a policeman. In the future, can I ask them to slide their police ID under the door before I open it? And what would be the best way to say this in Spanish?

DJ