I'm looking specifically when a missing person was considered deceased in 1850 (time lapse for example: Five years...seven years).
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The U.S. Constitution provides that all powers not expressly or implicitly assigned to the federal state are reserved to the 50 unitary states. The declaration of a missing person as legally dead thus falls under state jurisdiction unless there is a reason for the federal government to have jurisdiction (e.g. the party was military personnel who went missing while on active duty). Otherwise, there are 57 U.S. jurisdictions that comprise the United States, each of which has its own law on the question.
People who disappear are typically called missing, or sometimes absent. Several criteria are evaluated to determine whether a person may be declared legally dead:
The party normally must have been missing from their home or usual residence for an extended period of time, most commonly seven years
Their absence must have been continuous and inexplicable (e.g. the person did not say they had found a new job and were moving far away)
There must have been no communication from the party with those people most likely to hear from them during the period the person has been missing
There must have been a diligent but unsuccessful search for the person and/or diligent but unsuccessful inquiry into their whereabouts.
Declared death in absentia - Wikipedia
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According to Edgar Sentell, a retired senior vice-president and general counsel of Southern Farm Bureau Life Insurance Company, almost all states recognize the presumption of death, by statute or judicial recognition of the common law rule.
Some states have amended their statutes to reduce the seven-year period to five consecutive years missing, and some, such as Minnesota and Georgia, have reduced the period to four years.
If someone disappears, those interested can file a petition to have them declared legally dead. They must prove by the criteria above that the person is in fact dead. There are constitutional limitations to these procedures: The presumption must arise only after a reasonable amount of time has elapsed. The absent person must be notified. Courts permit notifying claimants by publication. Adequate safeguards concerning property provisions must be made in the case that an absent person shows up.
A person can be declared legally dead after they are exposed to "imminent peril" and fail to return—as in a plane crash, as portrayed in the movie Cast Away.
In these cases courts generally assume the person was killed, even though the usual waiting time to declare someone dead has not elapsed.
Sentell also says, "The element of peril accelerates the presumption of death." This rule was enacted after the attack on the World Trade Center, so that authorities could release death certificates.
Although people presumed dead sometimes turn up alive, it is not as common as it used to be.
In one case where this occurred, a man named John Burney disappeared in 1976 while having financial problems, and later reappeared in December 1982.
His company and wife had already received the death benefits—so, on returning, the life insurance company sued him, his wife, and his company.
In the end, the court ruled Burney's actions fraudulent.