I'm curious, since you have actual content-domain knowledge, would ND put themselves at any additional legal risk by simply saying that they are conducting such an investigation?
For context, I'm a UK lawyer, so I can't speak to the precise legal position in the US. The answer to your question is "potentially"; it depends on the circumstances and facts, of which we know very little. What follows is me speaking generally and not about this case in particular; I hope it will help shine a torch on how these things can play out behind the scenes. I warn in advance that this will sound cynical. Sorry in advance for long post.
The reality is that there are two aspects to how an employer deals with an employment-type issue. This is unlike many other areas of law. Because employment matters, by definition, involve people, the two aspects are (1) the "moral" or "ethical" part - essentially, doing the right thing; and (2) what is commonly referred to (by lawyers and businesspeople) as "the commercial" side. Sometimes these two aspects point in the same direction; many times, they do not.
Employers will always, from a commercial view, try to limit liability/exposure to potential liability, and other commercial detriment. That doesn't mean just legal claims; it also means potential loss of goodwill, sales, staff and so on.
If an employer does not receive a formal complaint about misconduct then it is generally under no legal (and usually no contractual obligation) to do so (at least in the UK).
If an employer is put on notice (I.e. is made aware) of allegations made by a former employee, then the very first thing to do, right away, is check the records: did that employee say anything to us at the time? The employer will check for formal complaints first, because those will (or should) be a matter of record, and easily locatable. Informal allegations - a private conversation, for example - will be harder to trace, and will take more time. A prudent employer will, however, search for both. But it will only make public the absolute bare minimum it needs to (or put another way, can get away with). The employer will hope that it can stop the matter there. SHOULD the employer, in an ideal world, speak to the former employee and conduct a full investigation of all the facts, and potentially take action against anyone found to have acted inappropriately? Of course. But that would, to come back to your question, open several large cans of legal worms, including potential claims from any employees disciplined as a result of this after-the-fact investigation, not to mention any other commercial repercussions. Of course, the employer will be taking the situation extremely seriously, and doing a lot of things behind the scenes, none of which will be made public, and I won't go into all that or this will become an essay!
I repeat, I am not commenting on the facts of this particular case, just providing some general info that may be of interest. Also, none of the above deals with any potential criminal matters. It is purely an employment law perspective.
