The FBI has special teams to assist in the search and recovery of missing children. Searching their site, there is no indication in the past which cases they were specifically involved with other then a few they reference. Recent articles suggest they were involved with the abduction of Ben Ownby but it is unclear if they were deployed in the disappearances of other high profile cases such as Destiny Norton, Bryan Dossantos-Gomes or Trenton Duckett which may be due to privacy issues.
It is the mission of the FBI’s Crimes Against Children Unit to provide a quick and effective response to all incidences of crimes against children. Making this a priority increases the number of victimized children who are safely recovered and reduces the number of crimes in which children are targets. The first few hours after a child is abducted are critical, and that is why the FBI has established the Child Abduction Rapid Deployment (CARD) Teams.
One common misconception is there doesn’t have to be a ransom demand and the child doesn’t have to cross state lines or be missing for 24 hours for them to be involved.