South Dakota first started tracking sex offenders in the state in 1994.
It requires anyone convicted of a serious sexually-related crime to register their personal information, including where they live, with their local law enforcement.
But not every sex offender follows those laws.
When convicted of a sexually charged crime, South Dakota law dictates a set of regulations those offenders must follow. One rule is that sex offender may not live in what's known as a community safe zone. That's 500 feet surrounding any school, park, pool or playground.
"If you look at those areas defined in that community safe zone, that's where there's going to be a large number of children, so the idea is to keep the convicted sex offenders away from those areas where children may be," Officer Sam Clemens of the Sioux Falls Police Department said.
To ensure sex offenders are not living in that area, they're required to register with law enforcement whenever they change their address. They must also register twice a year, once during their month of birth and again six months later.
"In Sioux Falls and the Sioux Falls area, we have a lot of sex offenders that live in the area so it takes a lot of time to keep track of these people and just to register them, I mean, every time they come in, it takes a fair amount of time to get them processed," Clemens said.
It's such a large task that the Sioux Falls Police Department has a detective who focuses solely on the registration and re-registration of sex offenders in the city. However, from time to time, those offenders don't properly register.
"It's not a daily occurrence but they pop up from time to time and he does a good job of keeping on top of the people knowing when they need to come in and register and when they don't come in, essentially they're out of compliance, he's already filling out the paperwork at that point in time," Clemens said.
That paperwork typically leads to charges, and to the state's attorney's office for prosecution.
"We do take all of them seriously, we work closely with law enforcement in prosecuting those cases but there certainly are those that are more serious than others," Minnehaha County State's Attorney Aaron McGowan said.
McGowan's office is in charge of prosecuting all sex offender registration violations in the county. The number of cases has been fluctuating by the year.
"We do have a significant number of violations in Minnehaha County. Back in 2007 we had well over 100 different felony charges relative to failure to register or similar violations," McGowan said.
Of the top five most common registry violations, Minnehaha County prosecuted 127 in 2007. That number dropped to 82 the following year and 71 in 2009. In 2010 that number dipped to just 50, then climbed back up to 80 last year.
McGowan says the most common violations happen when an offender forgets to register on time or after a move.
"So there's a lot of technical violations. We also do have violations where somebody is purposefully trying to avoid detection or commits a new crime while they've failed to register and those are the more serious cases," McGowan said.
Failing to register once is punishable by up to two years in prison, if it happens again it can carry a five year sentence. That's one tool lawmakers have given prosecutors as they work 12 months each year ensuring South Dakota's sex offenders, totaling more than 500 in Minnehaha County alone, follow their rules and regulations.
Eye on KELOLAND