IMO... The most interesting paragraph from your link (has nothing to do with searches):
"The usual working assumption in the case of most missing adults is that they are missing voluntarily and there is no need to actually look for them. (Legally, of course, any competent adult may simply choose to disappear.) However, every missing persons case carries the potential for the possibility of something more sinister, and as such, even a seemingly
simple missing adult report should be treated as having the possibility of leading to a more serious investigation. Like other cases, a missing persons case may go cold, but they are always remembered by the family and friends of the loved one. Even years later, some cold missing persons cases have been resolved by the locating of a wrecked car, with the missing subject still inside, for example. Other missing persons are actually the victims of homicide and any delay in investigating the report is also a delay in the homicide investigation. Care must be taken not to decide too quickly that a missing person, even an adult, is a voluntary walkway.
("Adults" Page 4)
** For those thinking "suicide", then wouldn't it fall under the category of "sinister" (as opposed to simply walking away)? So, again... why wait 3 weeks to search the home and surrounding area??