A Philadelphia lawyer was charged Tuesday with patronizing a sex-trafficking ring that held a missing 14-year-old girl captive and sent her to his downtown office to have sex with him.

The girl was held captive just blocks from her Philadelphia home in March 2012 and sometimes hired out 20 times a week, District Attorney Seth Williams said at a press conference. She was "sold" a month later to another pimp in Camden, New Jersey, before she turned up in Georgia that summer as a potential sex trafficking victim, a grand jury report said.

The girl has since told Philadelphia police that she remembered being taken to a law firm near City Hall several times, where a lawyer named Brian Meehan paid to have sex with her, according to the report.

The girl remembered the layout of the high-rise office and described security guards she saw in the lobby. She believed Meehan knew how young she was, but nonetheless paid her for sex and offered her alcohol while her handler waited outside, the report alleges.

Meehan, 56, a low-profile personal injury and criminal defense lawyer, surrendered hours before the charges were announced on Tuesday. He was charged with indecent sexual assault, patronizing an underage prostitute and other offenses.

"At this point, we're not privy to any of the facts that the D.A. alleges in the indictment because of the nature of the grand jury process, but my client maintains his innocence," defense lawyer Fortunato Perri Jr. said.

Investigators found DNA evidence during a recent search of the conference room at Meehan's law firm, the grand jury report said.

Meehan had previously represented the girl's alleged captors, Williams said. They have been charged and are in custody, but their names were not released because the grand jury has not yet finished its work on the case.

One of the alleged captors had seen the girl hanging around a high school in their Germantown neighborhood, and introduced her to a woman identified only as "S.F," the report said. "S.F." and her boyfriend, "R.H.," held the girl and four other females -- some of them minors -- at the house.

"They would beat her and threaten to kill her if she would try to leave," Williams said.

The girl's family had reported her missing. She turned up at a New Jersey hospital in April to get help for severe vaginal pain and told a nurse about her plight, the report said. But she gave a false name and disappeared before authorities arrived. However, she had listed her captor's address, which led police to interview the couple. They acknowledged that the girl had stayed there "in exchange for the victim having sex with men for money," the report said.

The FBI has also been involved in the case. Four others identified as victims of the couple have all been freed.

Williams and his deputies declined to say if Meehan's victim -- now 16 -- has been reunited with her family.