The Suspicious Astronomical Observation

Ran, Serena, and Conan go to watch the stars. Serena is especially hoping that she will see a shooting star. Ran has a friend at the observatory that helps her use a telescope; he introduces his senpais that work at the observatory. One of them just won an award known as the "Star Pioneer". However, that same night, that same person falls from the higher level of the observatory. Conan knows that this isn't an accident - but how can he prove it?