A man and woman from McAlester pleaded guilty in a federal sting, known as "Operation: Pappa Smurf."
"Smurfing" is a term used to describe people who hit up multiple pharmacies and drug stores, stockpiling the ingredients to make meth.
Larry Pirpich Jr. and Shila Parker had IDs from Oklahoma, Texas, Colorado and New Mexico, and would travel to those states to buy pseudoephedrine.
Investigators say the duo bought more than 6.5 pounds of pseudoephedrine over a two-and-a-half-year period.
It's illegal to buy more than one quarter of a pound per year in Oklahoma.
Pirpich and Parker could get up to 25 years in prison.