Joseph Horner, an Oceanside School District music teacher, faces a second-degree murder charge after his sister-in-law, Stony Brook University researcher Victoria Castle, was found unresponsive inside their shared North Massapequa residence. He has pleaded not guilty, and the disturbing allegations against him have not been proven in court.
A 911 call from a quiet Long Island neighborhood has developed into a closely watched homicide case involving two relatives who lived only one floor apart.
Nassau County police say officers responded to a North Oak Street residence in North Massapequa at approximately 8:44 a.m. on Monday, June 29, 2026. Inside the ground-floor apartment, they found 25-year-old Victoria Castle unresponsive and not breathing. Officers administered CPR before emergency crews transported her to a nearby hospital, where she was pronounced dead.
Police arrested Joseph Horner, 27, at the residence and charged him with second-degree murder. Horner, Castle’s brother-in-law and a music teacher in the Oceanside School District, entered a not-guilty plea during his June 30 arraignment and was ordered held without bail.
The criminal complaint initially made public lists a murder charge. Prosecutors, however, described additional allegations during the arraignment, including an alleged sexual assault following the strangulation. Those claims remain accusations that prosecutors must establish through admissible evidence and, ultimately, prove beyond a reasonable doubt if the case reaches trial.
What We Know About the North Massapequa Homicide
The North Oak Street property was divided into separate apartments. Horner and his wife lived in the upstairs unit, while Castle lived in the ground-floor apartment, according to police and court reporting. Horner’s wife was away when the alleged attack occurred, and authorities said she was not involved.
Prosecutors said Horner asked Castle to help him move a piano. Once she entered the area, he allegedly approached her from behind and placed her in a chokehold without warning. The prosecution claims he continued applying pressure until she became unresponsive.
Authorities further allege that Horner sexually assaulted Castle after she lost consciousness. Reporting from the arraignment states that prosecutors told the court Horner later acknowledged choking Castle and engaging in sexual contact with her. These allegations are among the most serious elements of the prosecution’s account, but no separate sexual-offense conviction or judicial finding has been made.
After the alleged attack, Horner called 911 and requested police and medical assistance, according to investigators. Responding officers found him outside the residence before locating Castle inside the lower apartment. Police took Horner into custody at the scene following their initial investigation.
Castle was transported to a hospital, where authorities said she died at approximately 9:25 a.m. The narrow period between the emergency call and her death will likely make the 911 recording, emergency-response records, medical findings and autopsy evidence central to the case.
Prosecutors Allege Years of Unwanted Sexual Interest
During Horner’s arraignment, a Nassau County prosecutor claimed he had experienced a sexual interest in Castle since 2017. Horner had reportedly known Castle since around 2016, when he met the woman who later became his wife.
The prosecution’s description suggests it may attempt to establish motive and premeditation through Horner’s alleged statements, digital communications, prior conduct or other evidence gathered during the investigation. A claimed long-term attraction does not independently prove a homicide charge, but it could become relevant if prosecutors connect it directly to planning, intent or the events of June 29.
Investigators will also need to establish the circumstances under which any alleged admissions were made. Courts frequently examine whether statements were voluntary, whether officers properly advised a suspect of constitutional rights and whether investigators accurately preserved the complete conversation rather than isolated portions.
Defense attorneys may challenge the meaning, context or admissibility of those statements. They may also seek access to the full 911 recording, body-camera footage, interview-room video, police reports and forensic evidence before deciding whether to ask the court to suppress any material.
For readers following the Joseph Horner and Victoria Castle case, this distinction matters. Prosecutors presented a forceful narrative at arraignment, but arraignments are not trials. They provide the court with preliminary allegations while the defense begins reviewing the evidence.
Victoria Castle’s Scientific Work Extended Far Beyond Long Island
Castle was not merely a name in a crime report. She was a geosciences researcher whose academic interests focused on understanding environmental and archaeological history through luminescence dating.
Stony Brook University listed Castle as a graduate student researching luminescence dating, geochronology and Quaternary science. The university’s Luminescence Dating Research Laboratory said her work used optically stimulated luminescence techniques to study archaeological timelines and environmental change across North and South America following the Last Glacial Maximum.
Luminescence dating allows researchers to estimate when minerals such as quartz were last exposed to sunlight or heat. Scientists can use that information to date sediments, reconstruct ancient landscapes and develop timelines for archaeological sites.
Castle had already built a record of academic achievement before entering doctoral study. Stony Brook previously recognized her as a geology researcher working under faculty mentorship, with ambitions to contribute to geochronology, geomorphology and Quaternary science.
She was selected as a 2023 Frances Velay Women and Science Research Fellow, a program supporting women conducting faculty-guided research in science and engineering fields. Stony Brook’s geosciences department also identified her as a recipient of fieldwork support for a project involving Folsom occupation and environmental change at Black Mountain, Colorado.
Those details provide a fuller account of what was lost. Castle’s death ended the work of a young researcher studying how physical evidence preserved in the earth can illuminate thousands of years of human and environmental history.
Oceanside School District Places Horner on Leave
Horner worked as a music teacher in the Oceanside School District. Following his arrest, Superintendent Phyllis Harrington said the district had placed the staff member on administrative leave effective immediately, pending further review.
The district emphasized that police had found no connection between the allegations and the school system or its students. It also acknowledged that news of the arrest was deeply disturbing for students, staff members and the wider community.
The administrative action is separate from the criminal process. Paid or unpaid leave, tenure proceedings and employment discipline operate under different rules from a criminal prosecution. A school district can restrict an employee’s duties while allegations remain unresolved without determining criminal guilt.
Horner’s public reputation as an educator has become part of the reaction surrounding the case. His attorney, Gregory Grizopoulos, described him as a tenured teacher whom students and colleagues regarded highly. The defense said the allegations contrasted sharply with the person known by Horner’s family and community.
That contrast may explain the intensity of public attention, but professional popularity does not establish innocence or guilt. Criminal cases depend on evidence, forensic findings, witness testimony and the legal instructions ultimately provided to a jury.
What the Second-Degree Murder Charge Means in New York
New York classifies second-degree murder as a Class A-I felony. The statute covers several legal theories, including intentionally causing another person’s death, causing death through conduct showing depraved indifference to human life, and causing a death while committing or attempting certain serious felonies.
Public reporting has not established which specific subsection prosecutors intend to pursue through an indictment. That choice matters because each theory requires the prosecution to prove different legal elements.
An intentional-murder theory would require evidence that the defendant intended to cause death. A depraved-indifference theory focuses on reckless conduct creating a grave risk of death under circumstances showing an extreme disregard for human life. Felony murder may apply when a death occurs during or in furtherance of certain listed felonies, including specified sexual offenses.
Prosecutors may present several theories to a grand jury when the available evidence supports them. The grand jury is not required to limit an indictment to the exact offense listed at the beginning of the investigation. Under New York law, it may authorize charges supported by legally sufficient evidence and reasonable cause.
That process could clarify whether Horner will continue facing only the publicly reported murder count or whether an indictment will include additional allegations. Until such charges are formally filed, reports should not describe him as convicted of murder or sexual assault.
The Evidence Likely to Shape the Case
The 911 recording may provide one of the earliest direct accounts of what happened. Its wording, tone, timing and consistency with later statements could influence how both sides construct their cases.
Investigators will likely compare the call with police body-camera footage, dispatch records and testimony from the first officers and paramedics who entered the apartment. Those records can establish the condition of the scene, the location of physical objects and anything Horner allegedly said before a formal interview.
Forensic pathology will be equally important. Medical examiners can document injuries, assess whether they are consistent with manual or ligature strangulation and determine the official cause and manner of death. Toxicology testing and other laboratory findings may also help rule out alternative explanations.
Evidence related to the sexual-assault allegation could include biological samples, clothing, bedding and laboratory analysis. The prosecution would need to establish not only that sexual contact occurred but also the circumstances under which it occurred.
Digital evidence may become another major area of inquiry. Phones, search histories, deleted messages, photographs, cloud accounts and location data can sometimes support or undermine claims about planning, motive and a person’s movements.
The defense can retain independent experts to evaluate the prosecution’s forensic conclusions. It may contest the cause of death, the interpretation of physical evidence, the reliability of alleged admissions or the state of mind required for second-degree murder.
A Not-Guilty Plea Preserves Horner’s Right to Challenge the Case
Horner’s not-guilty plea should not be interpreted as evidence that the allegations are false, just as the charge itself should not be treated as proof that they are true. The plea requires prosecutors to disclose evidence and prove every necessary element.
In New York felony cases, a grand jury generally determines whether enough evidence exists to issue an indictment and send the case toward trial. At least 12 grand jurors must vote that the evidence is sufficient. A grand-jury proceeding is not a determination of guilt.
After an indictment, a defendant is arraigned again on the formal charges. The case may then move through discovery, pretrial motions, evidentiary hearings, plea negotiations or a trial.
The defense could file motions concerning statements, search warrants, digital evidence or police procedures. Prosecutors, meanwhile, will continue assembling medical, testimonial and forensic evidence to support the narrative presented during the first arraignment.
Because the investigation remains active, the public record may change. Future filings could add charges, revise the prosecution’s legal theory or disclose facts that were not available when the arrest was announced.
