He was 38. She was 15. Their relationship started in cyberspace but quickly turned physical.

Dewey Edward Nelson, a Hillsville man who used the name "Jolly Rancha" on MySpace, was held up by federal prosecutors Thursday as a warning about the dangers of the online world.

"Take this issue seriously," Tim Heaphy, U.S. attorney for the Western District of Virginia, urged parents in a news conference held after a federal court hearing in which Nelson was sentenced to 13 years in prison.

Nelson, now 39, pleaded guilty in November in U.S. District Court in Roanoke to two counts each of taking a minor across state lines to have sex, and crossing state lines himself to commit illegal sexual acts.

Court documents and statements Thursday outlined how Nelson, a truck driver who also repaired computers, met a 15-year-old girl from Livingston, Texas, on MySpace. They began exchanging messages in December 2008, and in February 2009, Nelson rented a car, drove to Texas, and brought the minor back to Virginia. She stayed in his Hillsville apartment for about two weeks, and Nelson and the girl had sexual intercourse and oral sex numerous times, according to statements he later gave investigators.

Nelson told investigators, however, that he understood oral sex to mean talking about sex. Assistant U.S. Attorney Sharon Burnham said whatever Nelson's definition, it was clear there had been actual sexual activity.

Nelson told investigators that he had thought he was picking up a 19-year-old woman, but learned sometime during their time together that she was 15. The girl's mother came to Carroll County and took her home.

But Nelson continued telephone and online contact. In May, he drove to Augusta, Kan., where the girl had moved with her mother, and again brought her to Hillsville.

At some point, the girl was reported missing. Police in Kansas contacted the Hillsville Police Department to request a check of Nelson's apartment. The same day the call came from Kansas but 11 days after Nelson and the girl had returned to Hillsville, officers came to his apartment. Nelson told them he had not seen the girl they were looking for, and that the girl with him was his 13-year-old daughter.

Hillsville police checked with their counterparts in Augusta, Kan., and determined the girl with Nelson was the missing 15-year-old. Later on May 19, Hillsville police returned to Nelson's apartment and arrested him.

He had colored the girl's hair and acquired a false identification document for her, Burnham said.

Nelson's plea agreement said prosecutors agreed to the minimum prison term called for by sentencing guidelines or the mandatory minimum sentence of 10 years, whichever was lower. But U.S. District Court Judge Glen Conrad said a longer sentence was necessary to protect society from what seemed to be "a lifelong obsession" on the part of Nelson.

He noted that Nelson's two marriages, both of which ended in divorce, had been to very young women. One woman had been pregnant when she married Nelson, and her age indicated that the two must have been having sex while she was a child, Conrad said. Child pornography had been found on Nelson's computer when he was arrested, the judge said.

Testimony in Thursday's hearing indicated Nelson was sexually abused by a teenager when he was 7 years old.

Herman Dudley, Nelson's uncle and co-pastor of Mission Love Church in Galax, testified as a character witness and said that while he knew his nephew needed to be punished, he did not think he had done anything that every other man in the courtroom had not. And not long ago, it was common for women to marry young, he said.

Conrad replied that those marriages had tended to last, but Nelson had continued to seek underage partners.

Besides the prison sentence, Nelson was fined $750 and ordered to submit to five years of supervision by the federal probation office.