REVERE – A third arrest has been made in the Sept. 29 shooting death of Revere police officer Daniel Talbot.Gia Nagy, 17, of, Revere, was arrested Friday on a warrant by the State Police Detective Bureau and was charged with being an accessory to murder after the fact in Talbot’s death.Nagy will be arraigned today in Chelsea District Court and is the girlfriend of Robert Iacoviello, Jr., 20, who was previously arrested in connection with the murder.Iacoviello was arrested Nov. 9 on credible evidence developed in the course of an ongoing grand jury investigation.He was held at the Nashua Street Jail from Oct. 1 up until his arrest on weapons charges and a probation violation unrelated to the Talbot investigation.The State Police Detective Unit sought a warrant for Iacoviello’s arrest, who allegedly fired the shot that mortally wounded Talbot.Derek Lodie, 17, of Revere, was the first person arrested in the case and was initially charged with being an accessory before the fact. He pleaded not guilty during his arraignment.Talbot was shot once in the head as he socialized with other off-duty officers in a parking lot behind Revere High School in the early morning hours of Sept. 29.On the evening of Sept. 28, continuing into Sept. 29, Talbot and his fiancée Connie Bethell, 28, and three other members of the Revere police department left Margarita’s, a Revere bar, and proceeded to the bleachers behind Revere High School where they continued to drink and socialize.Lodie was apparently cutting through the field when he came upon the officers. The events that happened next have been the subject of intense scrutiny by homicide prosecutors, State Police homicide detectives and grand jurors.According to District Attorney Daniel Conley, evidence suggests that Talbot and his party exchanged words with Lodie, who left the scene through a hole in a nearby fence.Lodie then allegedly called Iacoviello and orchestrated the turn of events that would happen next.A short time later, Lodie returned to the scene and heated words were exchanged. Evidence suggests that Talbot and Officer William Soto began to approach Lodie when at the same time two young men and Iacoviello arrived at the scene.Armed with a 9mm handgun, Iacoviello fired the weapon and shot Talbot in the head. Officer Soto then discharged his weapon in response, as Talbot’s fiancée and Officer Stacey Bruzzese called for help.Iacoviello, Lodie, and the two men then fled the scene.An autopsy showed that the bullet that killed 30-year-old Talbot was not the same caliber as weapons that the other officers carried.