Imagine this procedure

Imagine this situation. You go to work. In the evening, you say goodbye to colleagues. You come home. And you find someone waiting for you.This someone wears khaki. This someone says he’s a cop. This someone begins to ask you questions about where you’ve been, who your friends are, do you know so-and-so? You say, no. He says you must come to the police station. You ask, why? He does not tell you