Twenty people have been rounded up, with more arrests expected, following an undercover drug-buying operation which targeted everything from marijuana and prescription pills, to meth and cocaine.“This is part of our ongoing drug operation,” said Sheriff Jackie Matheny, whose department worked the operation along with McMinnville Police Department investigators with help from the TBI and Meth Task Force. “These types of operations have led to the arrests of literally hundreds of people over the past few years.”Like many operations before it, the most recent operation used undercover operatives to purchase drugs from the suspects. The drug deals were monitored and recorded by lawmen who will use the recordings as evidence should the cases go to trial.