St Louis - Preparations for possible protests are set in St Louis, where a judge may rule on Friday in the murder trial of a white former police officer who fatally shot a black suspect.Jason Stockley's first-degree murder trial concluded August 9 and St Louis has been on edge awaiting Judge Timothy Wilson's ruling.Stockley testified he shot Anthony Lamar Smith in 2011 because he thought the drug suspect was reaching for a gun. Prosecutors say Stockley planted the weapon.Media reports and preparation announcements from officials indicate that Wilson may rule on Friday. Governor Eric Greitens has the National Guard on standby. Police are working 12-hour shifts, starting on Friday. All downtown courthouses will be closed, including the federal courthouse.Greitens and Mayor Lyda Krewson are urging calm. Also asking for peace is Smith's fiancée, Christina Wilson.