There are many offenses which require a person to register as a sex offender if convicted. Without going into detail, most of them are sexual offenses you would consider obvious. On the other hand, some charges labeled as sex crimes are not situations where you would consider the person deviant or dangerous at all. In either situation, sex offender registration can be a serious burden, making simple things like finding a place to live or finding a job nearly impossible. There are websites that will list sex offenders’ names and addresses, and in today’s internet age, there is almost no way to escape scrutiny. There is even a Sex Offender Tracker App for your Droid or iPhone. (OK, the video is pretty misleading, but it is funny, and don’t think the technology is too far from reality.)
As a result of the constant hardships, many sex offenders decide to just stop reporting. Alternatively, many flock to states with more lenient sex offender supervision, or simply to states with easy access to Mexico, or Canada. Federal Sexual predator legislation passed in 2006 allows U.S. Marshals to help the states round up the estimated 100,000 missing sex offenders, including 1003 arrests by federal agents in Texas to date. The effort to hunt down the missing sex offenders has been increasingly ramped up in the last few years, and different law enforcement agencies are working to better communications between themselves. A very informative article from Scripps Howard News Service explains how the missing Sex offenders have disappeared!, and where many of them have gone.