Using RFID / Geocache tags to trace child?

A friend's husband absconded with their child, and I've been trying to help her find him.  She thinks that if the father's parents were given or found a toy containing a trackable tag--like RFID or Geocache or something similar--that they'd secretly send it to the child, and that could be tracked. She is totally heartbroken and desperate.  I don't think that such a tag could be traced remotely across country, possibly even out of the country, unless you were in the immediate vicinity of the tag.  I guess that maybe even a short distance might help if the police were investigating a tip and wanted to make sure it was him, and they had some app that tracked the tag. 

This isn't a case where there's any issues about abuse--it just seems to be about jealousy and possessiveness, and my friend has already agreed not to prosecute the father if he'll just bring the child back and agree to shared custody.   Is there anyone who can explain what kind of tag would work in a situation like this?  I'm also a little worried that the father might scan the toy through his GPS and find the tag.

afaik, and RFID tag won't really work. you need to be in very close proximity to read it (like 10 feet).

that being said, i don't think this woman's husband would ever accidentally pick up on the RFID.

I still think it's hilarious that religious extremists believe that RFID is the mark of the beast. They had a vague understanding of a new piece of technology and instead of learning more, they went into a psychotic panic.

Suddenly when the same technology was in the hands of their own leaders, suddenly it wasn't as scary anymore. Hypocrisy at it's worst.

http://www.thenation.com/sites/default/files/user/248602/tmw2013-07-24colorsmall.jpeg

Is there any kind of tag that would work in this situation?  Sorry I am so ignorant about this stuff.

Let's say that the police find the child.  I notify them that I sent a toy with a particular RFID tag to a friend of the father's, and could they scan for it? That would show that the friend had helped the father, Would the police need a particular app on a smart phone or some other piece of equipment to scan for the RFID tag?

Would GPS work any better for the above situation?

Your help is much appreciated, thank you!

>>4
Well the Bible says something along the lines of the Antichrist forcing people to have the mark of the beast to buy/sell things.
And some information outlets like to make a big deal about RFID tags, and how you can have credit card info stored on them and them you just need to get your wrist scanned to buy stuff, to which they say that in the future, that is all you will need.
So it is not completely illogical for people to think that.

But the History Channel was the worst about it.
If I remember correctly, then one of their programs directly stated that RFID chips are going to be used to control the market and all that shit, along with all that Antichrist stuff.

Source: Catholic and used to watch History Channel.

Why fuck around with RFID?  Hide some tracking software on an ipad or suitable android device, pre-loaded with age-appropriate games for the kid.

>>6
That actually makes more sense.