Opening statements are scheduled for Monday.
Four co-defendants previously pleaded guilty in the case, and have either been sentenced or are awaiting sentencing.
Three of the defendants in the current case allegedly conspired in 2005 to kill the then-16-year-old victim, who had cooperated with investigators in a pandering case against Michael Ward.
Ward's 55-year-old mother allegedly helped him make third-party telephone calls from prison, which are illegal.
Michael Ward, 23, is charged with conspiracy to commit murder, conspiracy to prevent or dissuade a victim, and conspiracy to commit robbery, along with sentence-enhancing gang and gun allegations.
Hatchett and Jacques, both 24, are charged with conspiracy to prevent or dissuade a witness and conspiracy to commit robbery, along with gang and firearm allegations.
Prosecutors allege the plot was hatched after Michael Ward was sent to prison on a pandering case in which the teen testified against him. He ultimately pleaded guilty to pandering and received a six-year prison sentence.
While behind bars, Ward allegedly hatched the plot to kill the girl, who belonged to a prostitution ring he ran. The service advertised in the Temecula, Murrieta and San Diego areas via the Internet.
While in prison, Ward allegedly made more than 50 telephone calls to the other co-defendants, resulting in the conspiracy charges, according to testimony.