The Nogales High School student, whose name was not reported, was pulled out of class Monday after school officials received an anonymous tip, the Nogales International reported Tuesday. They found four packages allegedly containing $80,000 worth of heroin in the boy's backpack.
"This is an unprecedented amount," Santa Cruz County Sheriff Antonio Estrada told the newspaper.
The boy was taken to a county juvenile detention center, though Santa Cruz County Attorney George Silva said Arizona law would allow the 16-year-old to be tried as an adult.
"I don't have the reports. But obviously because of the amount and the fact that it was on school grounds, this is something we would look into," he said.
"It's another case where the traffickers use minors because they believe the consequences are not as severe," said Lt. Gerardo Castillo of the county's Metro Task Force. "But we fully investigate where the drugs are coming from and where they are destined. It's not just a matter of interdiction, but full investigations."