While it's strictly true that we haven't been told enough to know, I would expect even the most fair and reasonable of employment contracts to transfer the copyright to the employer by default if we're talking about a project that is in exactly the field that the employee works in at their job.

I have worked in and paid attention to employment law as far as it pertains to copyright in both California and New York. From what I have been told by competent lawyers in both states, this would be an open and shut case. Even if the contract didn't say anything about it (which would be extremely unlikely), work done by an employee on a project related to what the company does is a work for hire and therefore belongs to the company.