Barring evidence of criminality or being a danger to oneself, privacy and confidentiality laws generally protect the rights of those who elect to remain out of contact with family or friends.
These children are sometimes not registered anywhere and can become victims of crimes such as human trafficking or forced prostitution without any of their other relatives or local agencies knowing.
A study by professor Kenna Quinet states that the "most successful serial killers know to select the unmissed as victims if they intend to kill for an extended period of time", referring to serial killers targeting transient people, as well as those in institutionalized care, because their absence may not be easily noticed.
In the majority of US states, when foster children go missing their name is not publicly released and, with a few exceptions, child protective services representatives will not speak to the public—in some states, biological parents are not even permitted to contact the news media about their fostered child going missing.
Based on 2002 statistics, of the approximately 585,000 foster children in the US, 20% are missing at any given time, with 98% thought to be runaways and 2% (2,340) unaccounted for.