-- From Times staff reporter Jennifer Sullivan:

Shawn Clark, a 21-year-old West Seattle man who authorities said pimped out two teenage girls, then took all of their earnings to support his lifestyle, pleaded guilty in King County Superior Court today.

His plea was followed by guilty pleas from fellow West Side Street Mobb gang member Thomas Foster, 20, to four counts, including promoting prostitution, assault and conspiracy to commit prostitution; and Gerald Jackson, 21, to one count of promoting prostitution.

Clark, Foster and Jackson are the latest members of the West Side Street Mobb to enter guilty pleas after Seattle police, the FBI, the King County Sheriff's Office, as well as county and federal prosecutors, started investigating the gang last year for allegedly running a large juvenile prostitution ring.

A sentencing date has not been set for Clark, but his attorney and Senior Deputy Prosecutor Sean O'Donnell have agreed to ask a judge to give him a high-end sentence of nine years in prison. Defense attorney Brian Todd said that had Clark not taken the plea deal he could have faced prosecution in U.S. District Court, where convictions could have landed him up to 15 years in prison.

The nine counts against Clark include charges for promoting prostitution, violation of a domestic violence protection order, witness tampering and criminal conspiracy. He will serve extra time because the crimes were committed as part of gang activity, said O'Donnell.

In court this morning, Clark admitted that he sweet-talked a girl he had known since junior high school into working as a prostitute. He said that he told the girl he loved her, then made her work almost seven days per week in motels in Seattle and SeaTac, according to plea paperwork.

Since his arrest, Clark had the girl continue working as a prostitute with the goal of earning enough money to help bail him out of jail. Earlier this month, King County Superior Court Judge Helen Halpert raised his bail from $250,000 to $1 million and said that he could only use the jail phones to call his attorney because authorities had recorded conversations of him ordering the girl to go back to work for him.

Clark was among six men arrested last year when Seattle police vice officers conducted a sting operation and arrested a 19-year-old woman who had advertised sexual services on Craigslist. Officers soon learned about other teenagers and young women being used as prostitutes.

Clark's brother, DeShawn "CashMoney" Clark, was also arrested in the sting operation. DeShawn Clark is facing the stiffest charges, which include human trafficking, prosecutors said.

The Clarks' mother, Glenda Thomas, was recently charged with witness tampering after she allegedly called several of the prostitutes and told them not to talk to authorities. She also contacted another West Side Street Mobb member who has pleaded guilty in the case and threatened him, prosecutors said.

On July 17, West Side Street Mobb member Mycah Johnson, 19, pleaded guilty to promoting prostitution and has since been sentenced to 21 months in prison.

On Aug. 3, Desmond Manago, pleaded guilty to promoting prostitution. Manago, who has not been sentenced, is not a West Side Street Mobb member but is friends with the other men charged, authorities said.

Federal prosecutors say that the West Side Street Mobb was formed only three years ago but now has 50 members and associates, and has been tied to two fatal shootings and to bank fraud. A handful of members are currently being prosecuted in U.S. District Court.

Teen prostitution has become a growing problem in Seattle, according to a recent report.