Consult a business litigator. They'll want to review and discuss with you whatever employment agreement you've got with this employee, what proprietary information and/or trade secrets your company has and the steps you've taken to protect them, and what the investigation has disclosed.
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There are several potential avenues available to you to possibly bring legal action against your employee, the vast majority of which will be based in state law, so I would begin with a local business attorney. Also, I would take a moment to evaluate the "company confidential information" to ensure that it didn't include any employees' or external customers' personal information, as that (again largely under state law) may trigger separate reporting obligations for your company. Again though, depending on the type of information involved, a local attorney should be able to provide you advice on the best way ahead.
As the prior answers indicate, you need to consult a commercial litigation attorney in New York to help you evaluate your options. Your IT department needs to be involved immediately in making sure that everyone's relevant emails are preserved and that any deletion policy is suspended right away, but this preservation process should be supervised by an attorney. A good attorney will help you file for temporary and preliminary injunctive relief (a court order directing the employee to stop disclosing confidential information) and to seek monetary damages, potentially including punitive damages if your employee's conduct was quasi-criminal in nature (as it does sound based on your description of the facts). If you have a written confidentiality and/or employment agreement, that document will say a lot about your potential options here.
Another angle is to find out who has been receiving the confidential information, if anyone. If one of your competitors has obtained your proprietary information, you need a court order to stop the use of it and to direct that competitor to turn it over. Hopefully that hasn't happened yet, but you have to assume it will if you don't get a court order in place right away.
I strongly recommend that you retain an attorney immediately who understands complex commercial litigation in New York's state and federal courts. Every day that goes by is another day that your secrets are potentially exposed to the public, so this should be your top priority. Best of luck, and I hope you're able to get a good resolution here.
You should consult with a business litigation attorney, presenting the information you have, and he or she can prepare a lawsuit for breach of fiduciary duty. I have handled cases like this in the past.
You can't make her answerable for any crime. If you think one has been committed, you should report it to the DA at 100 Centre Street in Manhattan.
You can't force information from your employee. What you can do is sue her/him for damages and an injunction to prohibit her/him from sending or sharing information about your company to anyone without your consent.
You need an attorney for this. Find one who does a lot of work in civil/commercial litigation, and is up on discovery law. You have to be careful that you don't violate the employee's civil rights, so that you're not sued by the employee.
Your attorney should immediately go to court to seek a Temporary Restraining Order (TRO) which is an ex parte injunction that usually lasts until there can be a hearing on a preliminary injunction.
If you don't have a lawyer, ask around. If you don't find one that way, call the New York County Lawyer's Association on Vesey Street in Manhattan. (They're the little-known baby brother of the Association of the Bar of the City of New York, where all the big firms go. Solos and small firm lawyers belong to County Lawyers. The lawyers are every bit a good, but the dues are reasonable.) It doesn't sound like you need a mega-firm, with 3-4 lawyers working on a case at a time. This shouldn't have to cost you your shirt.
I am an attorney admitted solely in NY. None of the answers I submit on this forum constitutes legal advice, even to questioners in NY, and no attorney-client relationship is hereby created.
The employee's civil liability is going to depend, in large part, upon what type of information the employee misappropriated. New York courts generally protect the employer's protectable confidential information/trade secrets.
The employer's remedies against the employee can also be affected by any employment agreement that may have been executed by the employer and employee. For example, many employment agreements contain restrictive covenants that, if enforceable, can be used by the employer to prevent the employee from competing with the employer for a reasonable period of time and within a reasonable geographic area. The enforceability of any such covenant will depend on the facts of employer's/employee's situation.
In short, your available remedies against the employee will depend on the particulars of your business, the existence of an employment agreement, and what the employee actually did.