THE MISSING AND PRESUMED DEAD
Starting with the individual, we should note that albeit a relative few number of people vanish every year as if they had teleported to Mars, though that number still amounts to a significant workload for authorities; a significant degree of heartache for friends and relatives. One can divide missing persons into two categories; those who go walkabout involuntarily vs. those who of their own accord want to drop out and disappear from society at large.
1) People Who Go Missing Involuntarily
You can be kidnapped/abducted; sold into slavery; murdered and disposed of; die a natural, but unexpected death in an isolated place; or suffer an unnatural death by misadventure (swept out to sea; consumed by a man-eating tiger; fall into an icy crevasse).
‘Death by misadventure’ that results in missing person cases are those unfortunate individuals caught up involuntarily due to circumstances beyond their control. Someone can suffer a ‘death by misadventure’ where their remains are likely to be, if not inaccessible, at least unlikely to be found, far less recovered. These are cases of being in the wrong place at the wrong time. The presumed death by drowning of then current Australian Prime Minister Harold Holt is a case in point; another famous case is that of polar explorer Roald Amundsen or jungle explorer Percy Fawcett; Australian baby Azaria Chamberlain was allegedly snatched by a wild dog (dingo) - her body was never found. However, there is a certain percentage of missing person cases that, in all honesty, are truly baffling as we shall see.
2) People Who Go Missing Voluntarily
These include refugees who wish to escape from political, environmental, economic and other unpleasant circumstances; domestic runaways trying to escape an unpleasant home life or other personal unpleasant situations; fugitives on the lam; suicides who would rather not burden loved ones with their choice and dealing with the aftermath; those with mental illness who really aren’t accountable for their actions; those who want to change lifestyles (i.e. join cults) without letting others know;
By far and away, the vast majority of missing person reports involves those under 20. By far and away, those reported missing turn up again. Some don’t. At least if Australia is any guide, 95% of missing persons turn up again or are found within less than six months. But there are long-term missing persons, persons missing greater than six months. Overall, in Australia, about 0.17% of the populace go walkabout annually, but most resurface within a week. Other regions, like say the U.K., the percentage jumps to 0.36%. 行方不明 and cultural factors probably have a lot to do with differing statistics between countries.