It's a disturbing trend, the number of sex crimes against children doubled last year in South Dakota. More than one thousand sex related charges against children were filed in the state during the 2009 fiscal year, which ended July first. That's compared to 500 charges the year before.

Minnehaha County prosecutor Hope Matchan says her office is seeing more crimes committed as Sioux Falls continues to grow, but investigators are also working harder to keep those criminals off the street.

"It's a two-edged sword. It's good to see successful prosecution, it's good to see more cases being successfully prosecuted, but it's also very sad to see time and time again those crimes being committed," Matchan said.

Matchan prosecutes child sex crimes in Minehaha County, she says the increase is also thanks in part to people reporting the crimes.

"We're also going to see more reports of crimes as people become better educated. I think people are more willing to come forward in some situations and report those types of crimes than they were perhaps 20, 30, 40 years ago," Matchan said.

The biggest spike South Dakota saw last year was in child pornography charges. 637 charges of child porn were filed in 2009, that's more than four times the 137 charges filed in 2008.

Matchan says federal officials have put a larger emphasis on prosecuting child porn in the last year because they can get tougher penalties in federal court. But child porn has also become easy to access. 

"Child pornography is more readily available than it was and I think as it becomes more readily available, more people have computers, we will see an increase in that type of activity," Matchan said. 

And  while the numbers continue to increase investigators and prosecutors also hope it means more people are reporting the crimes and putting more sex offenders behind bars.

Matchan says officials are also finding new ways to investigate sex crimes, like logging onto chat rooms and arranging meetings with potential child predators, which also contributes to the increase.