The circumstances under which your last name was made part of the business needs to be explained more fully here.  In the mean time go and seek legal counsel as soon as you can.  If you do not answer the complaint filed in court a default judgement will be taken against you and then they will come after you personally for the money - maybe.  I say maybe becuase if this was a corporation there may be coverage there against personal liability.  But there are too many pieces of the puzzle missing here.  Have the attorney also explore the possibility that you were covered under an insurance policy, although thievery generally not insurable.