A Joint Base Lewis-McChord Army sergeant has pleaded guilty to child sex trafficking and could face 10-15 years in prison under terms of his plea agreement.

Sterling Terrance Hospedales, 27, was charged with sex trafficking of a child and attempted sex trafficking of a child stemming from an investigation last year by the Pacific Northwest’s federal Innocence Lost Task Force and the Lakewood police, as well as federal and military authorities.

Hospedales lured two runaway girls, ages 16 and 17, into prostitution and posted nude photos of the girls on the classified-ad website Craigslist in ads saying they would trade sex for money, according to the U.S. Attorney’s Office in Seattle. He entered his plea Tuesday in U.S. District Court in Seattle.

When he was arrested last year, he was assigned to the 4th Brigade, 2nd Infantry Division, and had been stationed at what then was Fort Lewis since March 2005. Hospedales also faces a dishonorable discharge from the military.

The investigation began in April 2009, when Lakewood police were alerted to a juvenile runaway from the Seattle area who was posting the ads.

Investigators from the federal task force that targets sex trafficking of children found both girls, who told authorities that Hospedales was their pimp.

The 17-year-old told investigators that she worked out of Hospedales’ apartment.

The 16-year-old said she was recruited by Hospedales in Wyoming and had arrived in Lakewood only a week earlier. She said she had photographs taken of her that were posted on the Internet, but she had not started earning money for Hospedales.

Hospedales, who is from Florida, was arrested as he left the Lakewood apartment.

Under the terms of the plea agreement, Hospedales is required to register as a sex offender when he’s released from prison.

He is set to be sentenced Oct. 25. The charges carry between 10 years and life in prison.