You are assuming that the offense occurred after the addition of criminal confinement was added to the registration requirements, which may have been in 1998. But it may not have been after. It might have been before for all we know. Until we know the date the crime was committed we don't know what law to look at to determine what registration requirement applied, if any. Hopefully the OP will tell us when the crime was committed. Or better yet, the OP ought to see an Indiana criminal defense attorney to have everything looked at and get advice. It's unwise for us to give definite advice as whether or not this offender had to register without ALL the facts.

