He should had said. "Look, I understand that this may be a normal thing you do, But all I can assert as fact right now is an adult and a child walking together at a rather unlikely time and I suspect human trafficking. I understand I could be wrong and so, I ask you to cooperate with me while we gather the facts."

Even if the father were to say that's not right or whatever. The cop has at the point clearly articulated his motive and intentions in a professional and respectful manner.

Fren I wish I could updoot this 1,000 times over. Thank you.