Why couldn't they find him?

I'm re-opening this thread from a few years ago.
http://www.imdb.com/title/tt0108149/board/thread/24333170?d=24333170&p=1#24333170

I see no answer in there, and there's a good chance I still won't get an answer.

Someone here provides as possible answer - that they could have talked to the detective and he wasn't helpful, I find that unlikely though.
http://www.imdb.com/title/tt0108149/board/thread/24001073?d=105742798&p=1#105742798


I don't understand how they were unable to locate or find out more about Paul. This part/flaw of the movie really bothers me. I felt the ending lacking, I just expected that more would happen and then the movie ended. It felt like the movie was building up to something more, but maybe it was just me.

Flan said that he called the detective (which lead to the police picking up Paul). To quote the movie "We hadn't counted on traffic, we promised Paul we would take him to the police. I called our new best friend - the detective." I assume they contacted him with a cell phone. They knew the detective's name, the police lady knew the detective was transferred, it shouldn't have been too hard to find where he was transferred to and to get into contact with him. Then the detective could have talked to whoever made the arrest (or just looked at the records) - got Paul's name (or whatever name he gave them), found out where he was taken, etc.