How is it possible

Via Virginia Department of Corrections facebook page:  "On 10/27, Augusta Correctional Center staff noticed a package protruding from an offender's backside during the exit search after visitation. Once the offender surrendered the package, staff found 427 Suboxone strips inside which have an estimated street value of $64,050." 

How is it possible that something was inside the offenders jumpsuit when it zips up the back. Not just that, but the facility to our knowledge has body scanners which would show a visitor carrying something in. How is it that it wasnt caught then?