For Sheriff, Son’s Investigation Not Over By LIBBY CUDMORE • Special to www.AllOTSEGO.com COOPERSTOWN – The County of Otsego’s investigation into Sheriff Richard J. Devlin Jr.’s correctional officer son ended when Ros Devlin resigned from his father’s department. But to the sheriff, it isn’t over. Tuesday, Sept. 29, the sheriff announced a DVD from the investigation is missing, and he’s asked District Attorney John Muehl to investigate the matter. In an interview, the sheriff said, separately, he’s also asking the…