wrongful termination??

My son , an assistant manager at a local restaurant, was immediately terminated after a sub-ordinate co-worker claimed she was ''unconfortable'' working with him. He was given no details as to who, what, when, etc., simply that allegations were made. Ironically these allegations were made a week or so after he (my son) recognized another sub-ordinate's hard work and trained her in a new area of responsibility. Does a company have a responsibility to perform a more equitable investigation when terminating under such strong allegations?