There is a legal presumption that an individual is alive until proven dead.  This means that the law assumes that a person is alive until a reason exists to believe otherwise. However, if evidence indicates that an absent person was subject to a particular "peril", they will be presumed dead after a statutory period of years, unless the disappearance can otherwise be explained. Typically this period is 7 years but it varies from state-to-state. Basically, a jurisdiction will not make the assumption that a missing person is dead unless it is reasonable to assume that the person would return if still alive.Additionally, most states require that a court will not rule that an individual has died without proof that a legitimate search for them was made.  During such a search, public records must be consulted wherever the person might have resided.  These records include but are not limited to: marriage licenses, death certificates, tax returns, or applications for government benefits.  The investigation must also include questioning of the missing person's friends or relatives as to their possible whereabouts.At this point, you should consult with an attorney as to the proper procedure for doing so in your state.