ALBANY — The 2019 murder conviction of Dolgeville resident Daniel Nellis in the 2018 murder of 21-year-old St. Johnsville resident Michaela MacVilla was overturned on appeal in a ruling issued Thursday. The Appellate Division, Third Department, ruling Thursday, without dissent, set the case on course for retrial. The appeals court overturned the Nellis' convictions based on multiple instances of what it found to be unchecked prosecutorial misconduct. Most of the instances cited by the court centered on the introduction and use by prosecutors of prior bad acts on the part of Nellis. Such bad acts usually must be the subject of…