Is your child suddenly speaking in an odd, slang-heavy language?

Is he or she becoming more secretive, turning up with unexplained amounts of money and wearing one particular color all the time?

It could be more than a case of typical teenage rebellion.

More likely, it means your child has gotten involved with a gang, said Detective Mark Finley, gang investigator for county police's special enforcement team.

"This is a world they don't want you to know," Finley told a crowd of about 200 residents at Brooklyn Park Middle School Thursday night. "If your child comes home and starts talking in a...