Investigators said brothers Aaron and Alfonzo Castro used money from the meth sales to buy comic books, including collector's items like first-edition Batman and Superman comics stored in protective plastic wrapping.

"What we are talking about is money laundering -- a means to have something of value that can easily be converted to cash but keeps you from having stashes of cash around," said Attorney General John Suthers.

Aaron Castro pleaded guilty to violating the Colorado Organized Crime Control Act, distribution of a Schedule II substance and criminal extortion.

According to the indictment, Castro and his organization distributed as much as 100,000 doses of methamphetamine per month throughout the Denver metro area.

Investigators believe the meth was being made in what they call a "super lab" in Mexico and smuggled to Colorado by way of Phoenix. Women were used as "mules" to smuggle the drugs into the states by hiding them in their body cavities, Suthers said.