Wouldn't it have been possible to find out via lab examination
- whether it was a fresh break or an older break;
- whether the window had been broken from the inside or the outside?
But iirc, neither S. Thomas nor J. Kolar mention in their books whether the broken glass was examined in detail and what the results were.
Direction of break (inside/outside) yes. The lab can determine which side force was applied to. I have not been able to find anything on determining the freshness of a break.
One of the most useful things would have been to examine the family members for tiny pieces of glass in their hair and clothing. When glass breaks, tiny particles go in both directions - the direction of force against the window, and back towards the direction of the person breaking the window. If a person was within 3 meters of the window when it was broken there would be glass fragments (tiny fragments, much like fibers) in their hair and clothing.
Clothing holds glass in much the same fashion as fibers. Woolens and knitted clothing will hold glass fragments better than smoother fabrics which will loose the glass fragments quickly.
There was of course no reason to test the family for glass fragments before the body was found. Up to that point it was a kidnapping case.