Usually there is a trap to cause a "de facto" admission. Or there is a debunking of the suspect's alibi.
This victim fell off the roof without making a cry or scream. Columbo already suspected foul play. Usually the murderer is someone who knows the victim. Columbo is looking for motive and opportunity.
According to Columbo himself, in one episode, as soon as there is a murder, someone almost immediately show up with a perfect alibi. Here of course, Findlay Crawford was "on stage" as the victim fell.
The elevator, the dust, etc., the timing, the noise on the recorded tape from the elevator motor...all suggest the method of the slats opening on the roof...giving Findaly time to set things in motion...but then be on stage as his alibi.
The enjoyment here is the character interplay and the sifting through "confusing" or 'troubling" little things.