The young woman told the courtroom that she was a normal high school student before she met the man a federal prosecutor called the “CEO” of the largest underage prostitution ring in the Washington region’s history.

She was 16 and had friends and enjoyed soccer, she said, but Justin Strom “brainwashed” her into believing that having sex with men for money was normal. He used flattery and promises of easy cash to lure her and seven other local girls into his operation.

The woman, who testified Friday before Strom was sentenced to 40 years in prison, said she would eat dinner at home with her parents and then turn tricks at night. She slid into addiction, dropped out of school, attempted suicide and had a child. Now, at 20, her life is upside down.

“He’s a con artist, a monster and a manipulator,” she said, sobbing, as Strom sat a few feet away. “I still feel broken and worthless. I feel like I’m at the bottom, and I can’t get out.”

Strom’s sentencing in federal court in Alexandria capped an effort to stamp out the Fairfax County ring, which prosecutors said was unprecedented in its scope, operated for about six years, made sophisticated use of social media to entice the girls and employed violence — including rape — to keep them working.

The operation, which was associated with the Underground Gangster Crips (UGC), recruited girls at Metro stations, on street corners and even in high schools. Strom, 27, of Lorton, also used fake accounts to approach hundreds of potential victims on Facebook and MySpace.

Prosecutors said the gang sometimes took girls door to door at apartment complexes in Northern Virginia, offering men 15 minutes of sex for $3o to $40. The girls were plied with drugs and alcohol, sometimes forced to have sex with five to 10 men a night and work seven days a week, according to court records. When they tried to leave the ring, Strom grew violent.

Strom was among five UGC members who were convicted on charges related to the ring. Another UGC associate, Henock Ghile, 23, of Springfield, was sentenced Friday to 10 years in prison. The gang was busted in March, after a months-long investigation by the FBI and Fairfax County police.

It was one of a handful of recent busts of gangs engaged in underage prostitution in the area.

“It’s an emerging trend we are seeing in Northern Virginia,” said Neil H. MacBride, U.S. attorney for the Eastern District of Virginia, who referred to Strom as the “CEO” of the prostitution ring.

A number of victims and their parents testified before Strom was sentenced, laying out in heart-wrenching detail the devastating effect that Strom had on their lives.

A former girlfriend who shuttled Strom around in her car said she once caught him having sex with an underage girl. When she confronted him, she testified, he lifted her off the ground by the neck and choked her in a hotel bathroom.

“This beast of a man had my life in his hands,” the woman said. “He would not hesitate to take my life if I did not do what he wanted.”

On another occasion, Strom forced a 17-year-old girl to use cocaine, cut her arm and then raped her, according to court documents. The girl was then forced to have sex with 14 men. Strom collected about $1,000 that night.

Defense attorney Thomas Carter said the image created of Strom was simply not accurate.

“He does not fit the profile of some big-time pimp,” Carter said. “He was living in a foreclosed house, where the electricity had been turned off. . . . He had $2 in his wallet and he was bumming cigarettes. . . . He was living in a perpetual fog of drugs and sex. There was no glamour.”

Before he was sentenced, Strom rose and apologized for what he had done. By the end, he was crying.

“I accept responsibility and am sorry for the pain that I have done,” Strom said. “I’m sorry for my actions.”