When a person who has been missing for an extended period is declared dead, even though there is usually no evidence to support whether they are alive to deceased because they are...well, missing.
A missing person is declared dead in absentia when they have not been located for seven years after vanishing.
Death in absentia can lead to odd scenarios if the person comes back.
For example, a man who had gone missing long enough to be declared dead suddenly turned up again and appealed his declaration of death in court. However, the decision was ruled irreversible, and he remained legally dead despite his clearly being alive, as he was standing in the courtroom!