An Oceanside School District music teacher is facing a second-degree murder charge after Nassau County police say he strangled his sister-in-law inside their North Massapequa home on Monday morning.
Joseph Horner, 27, was arrested at the scene at 285 N. Oak Street after he himself called 911 around 8:45 a.m. to request an ambulance for a woman inside the home.
When officers arrived, they found Horner waiting outside. Inside the first-floor apartment, they discovered his 25-year-old sister-in-law unresponsive. Officers and paramedics performed CPR before rushing her to a nearby hospital, where she was pronounced dead at 9:25 a.m.
The victim has been identified as Victoria Castle, also known as Allie, a Ph.D. student and research assistant in the geology department at Stony Brook University.
Just weeks before her death, she had posted online about completing another successful year with the university’s PCSTEM program, calling it a rewarding experience.
How the Attack Unfolded
The home on North Oak Street was split into two apartments. Horner lived upstairs with his wife, while Castle lived on the ground floor. Police confirmed that Horner’s wife was away at a bachelorette party at the time of the attack and had no involvement or knowledge of what happened.
According to a Nassau County prosecutor, Horner admitted that he had harbored a sexual attraction to his sister-in-law since 2017, the year after he began dating his future wife.
With his wife out of town, prosecutors say Horner saw an opportunity to act on those feelings. He allegedly asked Castle to help him move a piano in his apartment, then attacked her from behind without warning, placing her in a chokehold until she lost consciousness.
Prosecutors say he then moved her to a bed and sexually assaulted her before changing his clothes and calling police to report finding her.
Nassau County investigators said Horner acted alone and had no prior criminal history or previous contact with law enforcement. The investigation shut down the residential block for about twelve hours on Monday.
Community and School Reaction
Horner pleaded not guilty to the murder charge during his arraignment and is being held without bail.
His attorney, Gregory Grizopoulos, described him as a tenured teacher who is well-liked by students and colleagues, adding that the allegations do not reflect what those close to him believe about his character.
Both families were present in the courtroom during the emotional proceeding, with Castle’s relatives reportedly embracing and crying as details of the case were read.
The Oceanside School District confirmed Horner has been placed on administrative leave pending further review.
Superintendent Phyllis Harrington said in a statement that the charges are unrelated to the district or its students, and that the district remains committed to maintaining a safe and trustworthy environment for the school community.
If convicted, Horner faces a sentence ranging from 25 years to life in prison. The case remains under investigation, and no additional details about a motive beyond what prosecutors described in court have been released.
