Authorities on Tuesday completed the first successful prosecution under Colorado's anti-human-trafficking law, five years after it went into effect.

Dallas Colby Cardenas, 19, was sentenced to eight years in prison Tuesday after he was convicted of trafficking a child, pimping, pimping of a child and two other related charges for hiring out a 17-year-old girl into prostitution in May and June of 2010.

Following an indictment in October 2010, Cardenas was found guilty by a Jefferson County jury in June.

Colorado Attorney General John Suthers said he hoped the case demonstrates to prosecutors the ability to secure a conviction under the law, which was enacted by the state General Assembly in 2006.

More importantly, Cardenas' conviction revealed that one of the biggest stumbling blocks in getting a conviction under the law is recognizing the signs of trafficking and investigating them early.

"I firmly believe that there has been no reluctance on the part of prosecutors," Suthers said. "I think that in our investigations, we need to get a little more sophistication in what we look for when we run across these prostitution rings."

Former Colorado Senate President Peter Groff, who was the lead sponsor on the original bill, said he would have liked to have seen the law used earlier but was pleased to see it put to work.

Groff, who now serves as president of the National Alliance for Public Charter Schools in Washington, D.C., designed the bill to address human smuggling into Colorado from neighboring states.

"Whether it's immigration, children, women or anything, the law was meant to expand, and I'm glad we left it open to do so," Groff said.

Cardenas was convicted of forcing an 18-year-old woman and the 17-year-old girl to participate in prostitution in Denver and Lakewood.

Both were forced to pose for photos posted in sexually suggestive Craigslist ads and then coerced into having sex with individuals who responded to the Internet posts, according to the indictment.

Cardenas, who was 18 when the crimes happened, told the two to charge $175 an hour, or $150 every half-hour, and kept most of the money for himself.

Cardenas also forced the 17-year-old to have sex with him to prepare her for prostitution.

Proving coercion is critical and difficult in human-trafficking cases, Suthers said. Finding cooperative witnesses is even harder.

Those being trafficked often are hesitant to cooperate or feel threatened to report their circumstances, Suthers said.

"This is typically something that you stumble across," Suthers said.

While human trafficking may not be pervasive in Colorado, five years without a conviction is not an indication that there is any less of a threat in the state, Suthers said.

"I would never suggest that Colorado is the hotbed for this sort of thing, but we would be naive if we didn't think that there is human trafficking all around us — we just have to find it."

Jordan Steffen: 303-954-1794 orjsteffen@denverpost.com