What Happened
A Nassau County music teacher is set to face a sweeping new indictment after allegedly strangling his sister-in-law to death last month at their shared North Massapequa home. According to News 12 Long Island, Joseph Horner, 27, of North Massapequa — who taught at a school in Oceanside — will be indicted on two additional counts of murder and two counts of rape, as shown in court documents. The new charges come weeks after Horner was first accused in the death of Victoria Castle, 25, his wife’s younger sister.
Prosecutors say Horner orchestrated a pretext to get Castle alone. He asked her to help him move a piano into his apartment while his wife was not home — and then, once Castle was inside, he allegedly strangled her to death before having sex with her. Officials told News 12 Long Island that the residence on N Oak Street was a multi-family home divided into two apartments, and that Horner, his wife, and Castle all lived at that same address — with Castle in close proximity to the married couple at the time of the killing.
Horner has allegedly admitted to investigators that he had been lusting over his wife’s sister for years. Authorities say he told them that on the day of the killing, he saw an opportunity to follow through on what he described as his “sexual desire.” The admission, reported by News 12 Long Island, adds a layer of premeditation to the case that prosecutors will now bring before a Grand Jury.
Location & Road Context
The incident took place at a residence on N Oak Street in North Massapequa, a hamlet in Nassau County on Long Island’s South Shore. The address served as both the marital home for Horner and his wife and as the residence of the victim, Victoria Castle — all sharing a single multi-family structure split into two units. North Massapequa sits within the Town of Oyster Bay; for other incidents and road conditions in this area, see our Nassau County coverage.
Investigation & Legal Proceedings
Horner is scheduled to be arraigned on the Grand Jury indictment Wednesday morning, July 29, 2026, at Mineola court in Nassau County. The new charges — two additional counts of murder and two counts of rape — are on top of charges already brought against him following Castle’s death last month, per court documents reviewed by News 12 Long Island. The case was first reported by News 12, which has followed the prosecution since the initial arrest. The article was reported by Tara Rincon and published July 29, 2026, at 5:07 AM.
The expansion of charges to include multiple murder counts and rape counts signals that prosecutors are pursuing the most serious available charges under New York law for what they allege was a premeditated, sexually motivated killing. Horner’s own alleged admissions to authorities — including his stated years-long fixation on Castle — are likely to figure prominently as the case moves toward trial.
Broader Impact
Nassau County has seen a string of serious criminal cases originating in residential settings in 2026, including a bribery-linked Oceanside DWI crash case and a fatal Southern State Parkway DWI crash from earlier this month. The Horner case, however, is notable for the alleged betrayal of family trust involved — the victim lived under the same roof as her accused killer — and for the severity of charges now being pursued by Nassau County prosecutors ahead of Wednesday’s arraignment in Mineola.