Is the superintendent the sole decider of these cadets' fate or does he have to abide by UCMJ regulations??
Everything below depends on the actual facts of the incident and is a general outline of what might happen if the facts warrant.
All military members must abide by the Uniform Code of Military Justice.
A full investigation will be done by USMA, as well as by the appropriate civilian police authority.
The jurisdiction over the case and any criminal charges lies with civilian authority, since it did not occur on a military base. The local DA may turn it all back over to USMA to sort out and adjudicate. Or, the case, depending if there is one, will play out in civilian court, and USMA will await its turn.
Due process will be followed; the cadets will have rights. If USMA assumes jurisdiction, the JAGs will determine what, if any, charges will be brought. They cannot duplicate charges already brought in a civilian court that led to a verdict.
The Superintendent is likely the Army court-martial convening authority of the area. The case will be examined to see if there is enough evidence to support going to trial in an Article 32 hearing, similar to a grand jury proceeding. If there is, a decision is made with regard to a court-martial. I won’t get into the differences among General, Special and Summary courts-martial, except to say the GCM is most like a civilian trial. Outcomes of courts-martial may have punishments assigned that include punitive discharges such as the bad conduct discharge and dishonorable discharge. Military members being tried at a court-martial are presumed innocent.
The Superintendent also has the option of an administrative conduct proceeding, much more streamlined. Separation can also be the outcome of these, but it would likely be a General-Other Than Honorable conditions discharge.
There are two charges in the UCMJ typically not found in civilian law, but are very handy and flexible for military cases. Informally, they are “failure to maintain good order and discipline” and “bringing discredit upon the service.” This last one is especially handy for misconduct that brings mud splatter to the Army and USMA.
More than you ever wanted to know, but there is due process. The good of the Army will be a prime factor in all decisions.
If I recall correctly, the service Secretary is the separation authority, but generally follows the recommendation of the Superintendent.
Of course, I have no official knowledge of how any of this will play out, but my comments here are based on my time on the staff of a GCM convening authority, USNA Commandant’s staff and a whole pile of cases, more cases from when I was a CO, XO and Chief of Staff, doing Article 13 Non-Judicial Punishment hearings (the administrative option), being a Summary Court-Martial authority, serving as a member of 5 GCM juries, etc.
All this is just Misconduct 101. The facts of the incident have not fully emerged, and no doubt much will not be released to the public.