Both the prosecution and the defense agree that Robert Waters attacked and killed his fiancee's frail 90-year-old grandmother in their Centereach home.
State Supreme Court Justice Fernando Camacho will decide Tuesday whether a seizure caused Waters to snap in June 2011, as the defense claims, or as the prosecution alleges, he intentionally attacked and killed Florence Troiani.
Waters, 24, who has waived his right to a jury trial, is charged with second-degree murder.
"He's a murderer. Plain and simple. A murderer," Assistant District Attorney Glenn Kurtzrock said during closing arguments Tuesday at Suffolk County Court in Central Islip. "There is zero evidence to support that claim that he's not responsible. It's not there and they didn't prove it."
Suffolk police arrested Waters in June 2011 and charged with him with killing Troiani. During the trial, Kurtzrock said that Waters beat Troiani so badly that she suffered six broken bones in her back and a 2 1/2-inch rip in her heartA neuropsychologist for the defense testified last week that Waters suffered an epileptic seizure and therefore was not legally responsible for his actions.
"What's clear here is there's something wrong with his brain," his defense attorney, Anthony La Pinta, told the court in his summation at the end of the two-week trial.
"There is no motive. No motive for Mr. Waters to kill Ms. Troiani," he said earlier in the day. La Pinta said Waters killed Troiani while suffering from a "diminished capacity" in a seizure brought on and magnified by a recent withdrawal from the anti-anxiety medication Xanax.
The defense is asking for a verdict of not guilty by reason of mental defect.
Early in the session Monday, Camacho told attorneys that in addition to determining whether Waters is guilty of intentional second-degree murder, he will also consider two theories of first-degree manslaughter: when death is a result of the actions of an extremely emotionally disturbed person, and when someone intends to commit serious physical injury that results in death.
Waters trashed the house and was uncontrollable, La Pinta said during the trial.
La Pinta argued Waters had a blockage in a major brain artery at birth and suffered a head-on automobile collision in 2007 that caused a "brain bleed." Both made him susceptible to seizures, La Pinta said.
An expert for the prosecution countered that argument did not make sense because people having seizures cannot form words or make controlled actions.
"He knew. He knew," Kurtzrock said. "He knew exactly what he did."
Waters is due back in court Tuesday, and Camacho is expected to render a verdict.