how do you know if a window was broken from inside or outside?

Look where the shattered glass fell. If it is on the outside of the building then it was broken from inside. If it is on the inside then you can assume it came from the outside.

Look to see where most of the glass fragments are. Whatever force broke the window will tend to move the shards in the same direction. If they’re inside.. the window was broken from the outside .. if the glass is on the outside…. something inside broke it.

A high percentage of the glass would have fallen in the direction of the glass breaking. In other words if I break a window from the inside all the glass will be outside on the ground, well most of it anyway.

if theres glass on the outside then it was smashed inside the room, if theres glass inside the room then it was broken from the outside

if you broke the glass on the outside the glass will be on the inside and if you broke the glass from the inside the glass will be on the outside. think about it.

If it is a single layer of glass shards would naturally fall on the opposite side

on the broken edges of the galss you should see some wave like patters with a right angle on one side and more tangent/perpendicular on the other. there will be two directions of breaks radial( strait out from center of impact )and concentric( circular around impact ). radial edges will have right angles on the reverse side of impact

where the glass is – it’s on the opposite side from where the impact was.