Joseph Horner Case: Long Island Music Teacher Accused in Killing of Sister-in-Law Victoria Castle While Wife Was Away

 A quiet residential block in North Massapequa, Long Island, has been shaken by a case that prosecutors describe as both brutal and deeply disturbing, involving the death of 25-year-old Victoria Castle, a doctoral student at Stony Brook University. Authorities say Castle was found critically injured inside her ground-floor apartment on Monday morning after what they allege was a targeted attack inside the multi-family home she shared with her sister and brother-in-law.

According to the Nassau County District Attorney’s Office, 27-year-old Joseph Horner, a music teacher and the husband of Castle’s sister, has been charged in connection with her death. Prosecutors allege the incident unfolded while Horner’s wife was out of town. Investigators say Castle was home alone when she was approached under the pretense of helping with a household task before the situation turned violent.

Officials allege that Horner asked Castle for assistance moving a piano, a request that brought her into close proximity before he allegedly attacked her from behind. Prosecutors claim he restrained her until she lost consciousness, leading to a sequence of events that resulted in severe injuries. Emergency responders later transported Castle to a nearby hospital, where she died despite lifesaving efforts.

Court filings and statements from investigators further allege that Horner contacted emergency services himself shortly after the incident and remained at the scene when police arrived. Authorities say he allegedly made admissions during initial questioning, which now form part of the prosecution’s case. He has been charged with second-degree murder and is currently being held without bail as legal proceedings move forward.

The relationship between the accused and the victim has added another layer of complexity to the case. Horner lived in an upstairs apartment with his wife, while Castle resided below while pursuing advanced academic studies. Friends and neighbors have described the household as generally quiet, with no public indication of the allegations now central to the investigation.

Investigators have also referenced claims that the alleged conduct stemmed from a long-standing fixation, though those assertions remain part of the prosecution’s narrative and will be examined in court. Law enforcement officials have not publicly released additional evidence supporting motive, emphasizing that the case is still active and subject to judicial review.

The Oceanside School District confirmed that Horner has been placed on administrative leave pending the outcome of the criminal case. In a brief statement, representatives noted awareness of the charges and said the district is cooperating as needed while declining further comment due to the ongoing investigation and the seriousness of the allegations.

As the legal process begins, both families are left facing an overwhelming and deeply painful situation. Castle is being remembered by loved ones as a dedicated scholar with a promising academic future, while the accused awaits trial in a case that will now be closely watched across Long Island as prosecutors prepare to present evidence and establish what led to the fatal encounter.