Reader Paul Clarke proposed an RFID solution, which could overcome these difficulties. Citing the current level of integration of CCTV systems, he says: “If there was a similar initiative to link the RFID systems used by shops to catch shoplifters, it would be possible to search for an RFID tag that could be surgically implanted under a child’s skin or inserted into the fabric of their clothing.

“Potentially this could be an international initiative that would mean that if an abductor attempted to take a chipped child into a store that subscribed to the service, store detectives would be notified and by cross-referencing with CCTV footage one could determine the identity of the individual [abducting a child].”

Surgically implanting an RFID chip under a child’s skin seems a little Orwellian, though putting it into the fabric of clothes seems more acceptable. Are parents likely to go to such extremes to ensure kids are safe, or is it a step too far?
However, as reader Roger Bamford pointed out, one US firm has already designed a human-implantable RFID chip.

VeriChip has developed a passive RFID microchip, inserted under the skin by injection, which contains a unique 16-digit identifier. The number on the chip – which can be read with a proprietary scanner – could be used to access medical records, or determine whether someone has the authority to enter a secure area, the company says.

Verichip has also designed wearable active RFID chips, designed for use within care homes or hospital wards.
The chips sound an alarm if patients – for instance, those with Alzheimer’s – leave a designated area. It can even lock an exit as a patient approaches it. The chips can also be used to prevent the abduction of newborns by raising the alarm if the baby is removed from the ward.
http://www.eurekamagazine.co.uk/article/10637/Rapid-response.aspx