An 18-year-old accused of fatally shooting his ex-girlfriend in Nesconset appeared before a judge for the first time Thursday, as prosecutors detailed a disturbing timeline leading up to the killing.

Austin Lynch, 18, of Nesconset, has been indicted by a Suffolk County grand jury on a second-degree murder charge in the death of 19-year-old Emily Finn. Prosecutors say the two had dated for about three years and that Finn had returned home for Thanksgiving break when the shooting happened.

Lynch entered the packed courtroom without showing emotion. A large bandage covered part of his forehead, and a portion of his nose appeared to be missing from what authorities say was a self-inflicted gunshot wound. Finn’s family and friends, many dressed in pink, filled the courtroom, some crying as prosecutors recounted the events.

According to prosecutors, Finn went to Lynch’s home on the morning of Nov. 26 hoping for closure after their recent breakup. Minutes later, Lynch’s parents told investigators they heard gunshots. Prosecutors say Lynch used a family-owned semi-automatic shotgun to shoot Finn in the head before attempting to take his own life.

In court, prosecutors also said Lynch had been trying persistently to contact Finn after the breakup and had previously threatened suicide.

They cited a note found in his phone six days before the death, in which he wrote that he intended to “leave this place before my 18th birthday” and included explicit language stating he hated her.

Lynch is being held without bail and is expected back in court Monday in Riverhead.