DULUTH, MN (KDAL) - The Lake Superior Drug and Violent Crime Task Force along with investigators from the Boundary Waters Drug Task Force have been busy. Three people were arrested this week and charged yesterday in connection with the sale of heroin. Thirty-six-year-old Gilbert Dajuane McKenzie was arrested Wednesday after he sold approximately 14 grams of heroin to a cooperating witness who was working with investigators. He is charged with 1st degree sale of heroin. Officials say he was using the public bathroom at the Plaza Super One grocery store in Duluth to sell the drug to his customers. During the same incident, 22 year-old James Dalton Turner was arrested and charged for possession of a firearm by a convicted felon along with 5th degree possession of heroin. Turner was a passenger in a vehicle with other individuals who had also come to meet McKenzie to purchase heroin. In a separate incident on Thursday, investigators arrested 31 year-old Lamarr Derae Barber for selling heroin. During a search of Barber, investigators found approximately 10 grams of heroin. Barber is charged with 1st degree sale of heroin. All three individuals are being held at the St. Louis County Jail in Duluth.