Under Art 31, UCMJ, it is not proper for a commander to question a suspect about their involvement in a criminal act without first advising them of their right to remain silent.
So what you describe, this was a violation of Art 31, UCMJ.
The remedy for Art 31 violations is that the statement by the accused is excluded from court martial.
Basically, if you refuse NJP and demand court martial, your statement to the commander can be excluded. They can not use that statement at trial.
They can use other admissiable evidence...so, for example, if there is other evidence that shows you committed criminal misconduct the government can use that to prosecute you. But they can not use that statement you gave to the commander.
This will not prevent them from running NJP, if you accept NJP.
I am not sure what you are referring to about 72 hours...there is no rule that requires advisement within 72 hours, nor is there a rule that requries you get 72 hours to consider if to accept NJP. Basically, there is no "72 hour rule" relating to NJP. It souns like some sort of urban legend.
BotXXXXX XXXXXne: The interrogation by the commander was a violation of Art 31. They can not use that statement at court martial. But if they have other evidence that can be used at court, it may be they can convict you at court...so you want to consider that before refusing NJP
Best of luck Marine
Let me know if you have more questions