MONTEREY PARK (CBS) — Investigators want to talk to three men in connection with the murder of 15-year-old Brenda Sierra in October of 2002.

Brenda disappeared while walking to a friend’s house on her way to Schurr High School in Montebello on Oct. 18, 2002. Her body was discovered the following day in the city of Crestline, in San Bernardino County.

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“Because new witnesses have come forward, investigators were able to develop this,” Los Angeles County Sheriff’s Lt. Dave Coleman said.

One of the men investigators want to speak to was identified as George Barraza. Composite sketches of the other two men were released, and investigators believe they were known gang members who frequented the area where Brenda disappeared.

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KNX 1070’s Pete Demetriou reports sheriff’s investigators believe they have determined a motive behind the killing.

“This essentially is a retaliation for the community’s cooperation with law enforcement relating to other incidents,” said Coleman.

Coleman said Barraza is not a named suspect at this point.

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Brenda was a good student who had recently celebrated her Quinceañera just before her disappearance.