Being kidnapped, even if eventually released unharmed, must be a terrifying ordeal for the victims, and their friends and relatives. Some potential victims in Mexico are taking the precaution of having tracking devices injected into them.

The kidnapping rate in Mexico leapt almost 40% between 2004 and 2007. It now has the highest kidnapping rate in the world, having taken the lead from Colombia. We are talking about over 6,000 abductions, according to reliable estimates, although official figures suggest less than one thousand annually.

A local security company, Xega is offering to use a syringe to inject crystal covered transmitters, the size of a rice grain, under the skin. Pressing an external control then sends a signal to a satellite which then uses GPS technology to continue to track their whereabouts. The cost is $4,000, with an annual renewal fee for the tracking capability of $2,200. Sales are apparently excellent.

One happy customer, identified only as 28-year old Cristina, was implanted along with seven other members of her family last year as a “preventive measure.”
“It's not like we are wealthy people, but they'll kidnap you for a watch ... Everyone is living in fear,” she said.

Xega designed global positioning systems to track stolen vehicles until one of the owners of the company was kidnapped in broad daylight in 2001. Frustrated by his inability to call for help, the company adapted the technology to track stolen people.

The company don’t (yet?) have a patent specification but others had earlier thought of the idea. One such is by Ronald Clark of Missouri, who in 2002 applied for what is my Patent of the Month. I chose it partly because it has rather attractive drawings.

 
They show two soldiers using a tracking device, linked to a satellite, to identify the location of the victim, held by two men. The implanted transponder has a piezo-electric battery that is recharged by using the potential electrical energy generated by the body of the host, such as the movement of muscles. This, in theory at least, overcomes the potential drawback of any such devices: the transmitter needs to retain power so that it can continue to be able to transmit. The implanting process sounds rather painful.

The patent states that a voice activation feature similar to voice dialing in cellular telephones could be included in the transponder and would allow the user to unilaterally activate the transponder by stating a predetermined password. I’m not sure if that would actually work (patented inventions don’t have to be able to work, just new). How would the transmitter pick up the words – and what if you actually set it off by accident by saying the password, or a visitor says them.

The concept of a hidden method of control does have an advantage over the Mexican idea, so long as the victim is not immediately gagged. In both the transmitter would be hidden, but the Xega device has a control device that would be found in a search (unless it was such that it could be discarded without being noticed). The kidnappers might quickly release the victim – in which case a dummy control device would be just as good – or they might murder him or her out of frustration.

The general idea was not new to Clark. In 1998 Medtronic Incorporated filed for US 6083248. The idea was to track by satellite wandering, “at-risk” patients. It is not known if the Clark invention has actually been used.

Our Patent of the Month is provided courtesy of Steve Van Dulken from the British Library.  Steve is a patent specialist at the British Library and has his own blog at http://britishlibrary.typepad.co.uk/patentsblog/

Steve has worked since 1987 as a patents librarian at the British Library. Author of Inventing the American Dream, Inventing the 19th century and Inventing the 20th century, both popular science, and of British patents of invention, 1617-1977: a guide for researchers and editor of Introduction to patents information.