The man accused of killing 14-year-old Zyaire Fernandez from Mount Vernon faced a judge on Wednesday. The mother of Fernandez quickly walked out of the courtroom as soon as the hearing began, apparently unable to stay in the same room with Tyrese Coghiel, the man accused of fatally shooting her son.  Investigators say Coghiel fatally shot Fernandez on March 9 in the courtyard of the Levister Towers apartment complex at 10:30 a.m.The ninth grader, who attended school at the Mount Vernon STEAM Academy, was rushed to the hospital but died shortly after arriving.  Several days later, detectives tracked Coghiel to a cousin's Brooklyn apartment where he was arrested.  He pleaded not guilty to charges of second-degree murder and criminal possession of a weapon - both felonies.  The 21-year-old Mount Vernon man had already been arraigned after his arrest last week.   Wednesday's court appearance had to do with switching attorneys.  There was some sort of conflict with Cogheil's legal aid attorney, so a new lawyer had to be assigned to the case.The family of Fernandez is preparing for this Friday's funeral services at the LIVE Church in Mount Vernon.The next court appearance for Coghiel is scheduled for April 14. He was remanded back to the Westchester County Jail where he is being held without bail.