The Mysterious Height Difference of 20 cm

On a walk with Ran, Conan runs into Takagi who explains that Katsugoro Kitamura, the president of a construction company, is found dead from a stab wound. The suspect, Yuuichi Minamida, is in custody while the police attempt to figure out how the murder was done. The knife angle on the body suggests Kitamura was murdered by someone shorter than him; Minamida is 20 cm taller than Kitamura making it technically impossible.