In January 2006, Mulholland was appointed by Lord Advocate Colin Boyd as Area Procurator Fiscal for Lothian and Borders, the head of the Procurator Fiscal Service in that sheriffdom. In this role, he oversaw the high-profile trial for the 1977 World's End murders, which was thrown out of court by the trial judge, Lord Clarke, due to a lack of evidence. The Lord Advocate at the time, Elish Angiolini, made a statement to the Scottish Parliament, saying she was "disappointed" at the decision. This was criticised by Lord Justice General Lord Hamilton, head of the Scottish judiciary, who said it undermined the independence of the judiciary.