Tonight, there are new clues in that royal mystery. Who snapped those stople ltopless photos of the duchess of cambridge? Now the focus has shifted to the man on the other side of that super-powered... See More
Tonight, there are new clues in that royal mystery. Who snapped those stople ltopless photos of the duchess of cambridge? Now the focus has shifted to the man on the other side of that super-powered lens. He could face steep fines, even prison. Tonight, we show you just how far you can see with one of those telephoto lenses. Abc's jeffrey kofman is in london tonight. Reporter: London tabloids call him the rat. The man who snapped the infamous shots of kate topless. French police are hunting for him. We tracked down his friend, fell local photographer pascal, who would only say le rat is actually from ireland. Of course, we don't want to reveal the name of a -- it's not a friend, a journalist. Reporter: The scene of the crime? This $24 home where the royal couple were vacations. The pictures were taken half a mile away with a super telephoto lens. A website shows what it can do. Those two dots in the distance, now perfectly clear, up close. The photographer using it was shooting for "closer," a paris magazine, paid just $6500. If he had been working on his own, he could have sold those pictures for $300,000. We went to the paris offices of that magazine and asked for an interview with the editor, who has said violating kate's privacy is no big deal. She's not doing interviews? The editor seems to value her own privacy. But if the photographer is identified, he could be in big trouble. The french law is very clear, that taking pictures in a private place without the consent of the person concerned is a crime. The penalty? One year in prison, and a $60,000 fine. Does pascal think his friend crossed the line? Not a bit. I don't know one photographer on the planet who don't want to do this kind of picture. Reporter: Lawyers say the magazine can't be forced to reveal the name of the photographer, but if the police really want to find him -- they can. Jeffrey kofman, abc news, paris.
This transcript has been automatically generated and may not be 100% accurate.