SAN FRANCISCO — When ex-Stanford University swimmer Brock Turner became a registered sex offender for life last Tuesday, he joined a nationwide list of registered sex criminals that has grown dramatically in recent years to more than 800,000.

Even some who have denounced Turner’s six-month jail sentence as too lenient for sexually assaulting an unconscious woman question whether he should spend his life with the stigma and onerous restrictions of a registered sex offender.