BOSTON – The fourth person to be arraigned in Suffolk Superior Court in connection with a police officer’s murder last September pleaded not guilty Tuesday to charges she helped dispose of the murder weapon.Gia Nagy, 17, 98 Eastern Avenue, Revere was indicted by a Suffolk grand jury Dec. 20 on charges of being an accessory after the fact to murder.”She is completely innocent of these charges. I look forward to reviewing the government’s evidence,” said Michael Doolin, Nagy’s attorney.Nagy was released on the $10,000 cash bail she posted at her initial arraignment Dec. 17 in Chelsea District Court. At that arraignmentprosecutor John Lacey said Nagy helped boyfriend Robert Iacoviello, who was charged with fatally shooting Officer Daniel Talbot, prepare an alibi.Lacey also said Nagy helped dismantle and dispose of the 9-millimeter handgun used to kill Talbot on September 29.”Witnesses also testified under oath that Gia Nagy knew that the weapon was the same weapon that was used to kill Daniel Talbot,” State Police Det. Steven McDonald stated in a report filed in court.Police investigating Talbot’s death recovered pieces of a handgun from storm drains on Cushman Avenue. Prosecutors claim Nagy dumped the pieces down the drains.After her District Court arraignment, Nagy’s attorney said she assisted efforts to investigate Talbot’s death, including answering questions from police and being called twice before the grand jury investigating the murder without being asked to testify.Two other Revere residents have been charged in connection with Talbot’s death in addition to Iacoviello and Nagy. Derek Lodie, 17, is charged with being an accessory before the fact to murder and James Heang is charged with being an accessory after the fact and unlawfully carrying a firearm.Lodie, Iacoviello and Heang are due back in Superior Court on Jan. 15. That appearance may be rescheduled to Jan. 17 when Nagy is slated to return to court.