A Canistota mom contacted us, wanting to know why a convicted sex offender was allowed inside the public school to get his son's homework.

She was under the impression state law kept sex offenders away from schools, parks and pools.

It does, but as we found out, only to a point.

Under current rules, convicted sex offenders are supposed to stay 500 feet away from schools, parks and pools.

But the way South Dakota law reads, offenders can freely visit those areas if they have a valid reason.

In Canistota, Darin Nugteren...convicted three months ago of sexual contact with a 15 year old girl.. entered the public school last week to pick up his sick son's books from his locker.

We checked with the state attorney generals office and found, under state law, it's a valid reason. No law was broken.

Also, if a sex offender wants to go jogging and runs through a park where kids are playing, it's allowed under state law.

But, if an offender is in a safety zone area and is found loitering, that's where state law kicks in and the offender could find themselves in trouble.

We're going to stay on this story to find out if South Dakota lawmakers think rules for sex offenders should be tightened up or stay the way they are now.