So, the person did something awful in hir past. Sie's presumably made up for it. In jail, in classes, in community service, etc. Plus all the bells and whistles of being a registered sex offender.
I think it's perfectly reasonable for police to go asking questions of registered sex offenders whose past crime(s) have fit the MO of the missing child (i.e. question a man who's offended against an 8 year old boy in a case of a missing gradeschool boy, but leave the 22 year old who had sex with his underage girlfriend alone), but it's bull to search them or their home without consent or a warrant, and it's bull to get a warrant just because the person is a sex offender.
I think it's perfectly reasonable for police to go asking questions of registered sex offenders whose past crime(s) have fit the MO of the missing child (i.e. question a man who's offended against an 8 year old boy in a case of a missing gradeschool boy, but leave the 22 year old who had sex with his underage girlfriend alone), but it's bull to search them or their home without consent or a warrant, and it's bull to get a warrant just because the person is a sex offender.