...one has to ask, who makes decision in any military group? Is it the chain of command? I am guessing the answer has to be 'yes'.

Did that chain of command excercise an order to stand and fire?

Well, none of the records I have read indicate that the command to fire was given in any legal understanding of the word. The National Guard did not acknowledge that such a command was given.

So basically, you have a small bunch of ill-disciplined men with guns shooting at essentially weaponless people, killing or wounding anyone they hit, regardless of their culpability in any crimes, imaginary or real, from that moment or previous situations like the rioting in town in the days preceding.

It is not against the law to go to university, especially at exam time.

I would be interested in reading the accounts by the soldiers who actually fired on the students that day.