Conan's not as smart as we think
Honestly, you're a great detective? How could you fall for such a simple trick?
Clip from the Lupin III vs Conan special. And that is not Ran, it's a princess that just happens to look a whole lot like her and stole her clothes. The princess has lighter colored hair and eyes and is two years older than Ran. Sorry for the lack of subs, the only subs i can find are horrible. Half of the things said /aren't/ subbed.