MANKATO, Minn. – An ongoing investigation into drug dealing has led to the arrest of someone law enforcement describes as a “persistent offender.”. The Minnesota River Valley Drug Task Force (MRVDTF) says it has worked with local enforcement agencies to again apprehend Roberta Florene Brown, also known as “Miss B.” MRVDTF says Brown has been implicated in more than seven narcotics-related cases across multiple counties since 2019.