Actually, they do not prepare a body for burial, but rather they prepare the family for the memorial service. If there is a will, the attorney does all the prep.
The funeral home takes the body and prepares it. You go to the funeral home and tell them what you want and the clothing that you want on the person. You pick out the casket and flowers. The rest is handled by the funeral home. They can even help you with the insurance and getting death certificates.
