Well, whatever the article, i'ts no good:
1) The cell-phone net has the potential to trace and record the whereabouts of a device similar to a cell-phone, but only to cell level. The size of a cell varies from some hundreds of meters in cities to several kilometers in open country. Also, there is some uncertainty: A device chooses which cell to log into based on signal strength; its not unusual for cellphones to log to neighbooring cells due to local conditions.
2) A cellphone contains a fairly powerful transmitter (0.5-2W). This requires power, which is derived from a battery that needs recharging every few days. An implantable chip can have no power source, its tiny transmitter gets power from radio waves beamed at it from a short distance and even then its weak signal can only be picked up over a very short range, I wrote a few feet; this might without too much trouble be extended to several meters, still ---
The essense of the matter is: If, like you suggest, a severe punishment sceme is to be based on electronic tracking, it requires a very precise and reliable system. Otherwise you wont get the feeling of safety and security by the general public which I assume you are aiming at, in spite of your bloodthirsty attitude.
The ability to prove that somebody has been in the neighboorhood of a crime will at best serve as circumstantial evidence, and you cannot punish people for eluding tracking as long as there are numerous blackouts in the net, like in the cell-phone net.
There are a number of purposes where electronic tracking of persons can be useful and beneficial, but not as the basis of a "kill'em all" penalty system. And, I might add, such penalty systems, regardless of enforcement method, has not been shown very successful for abolishing crime. There was a time when they used to hang pickpockets, but that didnt guarantee a low crime-rate.