DANBURY—A Danbury man was arrested on drug charges Friday after police received complaints that he was selling drugs around the city. Officers began investigating Elbion “Mark” Barnes, 27, two weeks ago after they received complaints that he might be selling illegal drugs from various locations in the Danbury area. Based on surveillance and other investigative techniques, police determined that Barnes’ activity was consistent with drug trafficking and they received search and seizure warrants for him, his phone and his home. Friday, police arrested Barnes after surveying locations he is known to frequent and following him to a gas station on Newtown Road.