The friend of a 15-year-old girl raped , bludgeoned to death and dumped in a wooded valley on her way to high school in 2002 has been charged with murder . Los Angeles County police say it is a major breakthrough in the cold case of Brenda Sierra - who they believe was slaughtered in a brutal act of gang revenge . Just ten days before the killing in October 2002 , Brenda 's brother had testified in a drive-by shooting case . Now police say her friend Rosemary Chavira , also 15 at the time , 'coordinated ' her kidnap by possible street gang members and watched them sexually abuse and kill her . Scroll down for video . Cold case : Brenda Sierra , 15 ( left ) was kidnapped , raped , bludgeoned to death and dumped in a valley in 2002 in a suspected act of gang revenge . Her former friend Rosemary Chavira ( right ) is charged with murder . Mourning : File footage of Brenda 's funeral . Her family have had to wait 13 agonising years for answers . Officers also have three male 'persons of interest ' , two of whom are now in custody being questioned . The third , named as George Barazza , is believed to have fled to Mexico . In a previous appeal they said Barazza 'may travel back and forth across the border ' and was also wanted on a 'no-bail ' arrest warrant for a prior narcotics conviction . Police say they expect charges to be filed against three men in the next month . Chavira , now 27 , was arrested on Friday near her home in Lancaster , California , over the murder , which took place when the pair were living among the Hispanic community in East Los Angeles . In Mexico : George Barazza is the only one of three male 'persons of interest ' to have been named . The Los Angeles County District Attorney has filed charges of special circumstances of felony murder during the commission of a kidnapping and rape and gang allegations . LA County police lieutenant Dave Coleman told a press conference : 'She actually was a friend of Brenda at the time and coordinated the kidnap itself , and evidence indicates to us that she was present during the rapes and during the murder . 'Her brother had testified in a drive-by shooting approximately ten days before her kidnapping . ' Because she was 15 years old at the time of the murders , Chavira faces life in prison without parole if she is convicted . She pleaded not guilty at an initial hearing yesterday . Brenda was walking to a friend 's house on her way to Schurr High School when she was abducted in the street at 7.30am on October 18 , 2002 . Her body was discovered the next day in the Valley of Enchantment area of the City of Crestline , in San Bernardino County . The San Bernardino Sheriff ’ s Department investigated the brutal murder for six years before it was passed over to the detectives of Los Angeles County . Despite the offer of a $ 150,000 reward and the release of composite sketches of two male suspects in 2012 , an arrest was never made . But detectives persisted with the case , using new DNA technology , surveillance footage , witnesses and clues from gang members who had relinquished their criminal past . For the first time , officers now believe they have a timeline for Brenda 's final hours . They say she was kidnapped in the area of Whittier Boulevard and Leonard Avenue in East Los Angeles . Questioning : These composite sketches of two male suspects were released almost three years ago . Now police say they are questioning two men and expect to bring more charges within the next 30 days . Solemn : A floral memorial to the murdered teenager . Just ten days before the killing in October 2002 , Brenda 's brother had testified in a drive-by shooting case . Now police say Chavela 'coordinated ' the kidnap . She was taken to a home in nearby Williamson Avenue , where she was sexually assaulted . She was then moved again to another home in Miller Avenue , where she was bludgeoned to death . Her body was later transported out of the city . Witnesses saw a 'suspicious , dark , SUV ' in the area where her body was found , while other witnesses near Brenda 's home saw 'one or two females ' talking to her in the street . The case is another agonising twist for Brenda 's mother Fabiola , who has waited 13 years for answers over her daughter 's senseless murder . An LA County police spokesman claimed the force has 'worked tirelessly to bring her killers to justice ' . They are still looking for outstanding witnesses . Lt Coleman said : 'We hope that anyone with knowledge of this horrific incident will overcome any fear of coercion or retaliation and come forward and bring justice to Brenda and her family . '
Brenda Sierra was raped and body dumped in a wooded valley in 2002 . Now police have filed charges against former friend Rosemary Chavira . Officers say Chavira 'coordinated ' kidnap and witnessed rapes and death . Three men are also suspected - two are in custody and one 'is in LA County ' Police have long believed crime was an act of revenge by a street gang . Brenda 's brother testified over drive-by shooting 10 days before she died .