After four months of undercover work, Lancaster County sheriff’s investigators and deputies fanned out across the county Tuesday to round up 28 drug suspects. By the end of the day, they had arrested 15 of them on 48 charges, plus four people charged with other offenses unrelated to the Drug Task Force’s work. According to the arrest warrants, each of the drug suspects had been involved in an undercover transaction between October 2017 and February 2018.