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New York Music Teacher Accused of Murdering Sister-in-Law After Years of Alleged Obsession

Prosecutors allege a 27-year-old music teacher strangled his sister-in-law, a Ph.D. student, after luring her to his home.

July 1, 2026 · U.S.

New York Music Teacher Accused of Murdering Sister-in-Law After Years of Alleged Obsession

A music instructor in New York is facing charges for the alleged murder of his 25-year-old sister-in-law, a doctoral student, following what prosecutors describe as a decade-long obsession.

Joseph Horner, 27, has been charged with second-degree murder in connection with the death of Victoria Castle. Nassau County police discovered the Stony Brook University doctoral candidate unresponsive at a North Massapequa residence on June 29.

Court documents filed in Nassau District Court, specifically a felony complaint, state that Horner intentionally caused Castle's death, though specific details of the allegations were not immediately provided within the complaint itself.

Allegations and Discovery

During Horner's arraignment, prosecutors from Nassau County reportedly asserted in court that Horner had harbored an "obsession" with Castle for over ten years.

Furthermore, prosecutors alleged that Horner enticed the Stony Brook University Ph.D. student to his home under the pretense of needing assistance to move a piano, knowing his wife was away on a bachelorette trip. They claim he then subjected her to a chokehold, sexually assaulted her, and strangled her.

Statements made by prosecutors also indicated that Horner placed a 911 call following the incident, remained at the residence until law enforcement arrived, and confessed to detectives that he was responsible for Castle's death.

Nassau County police reported that officers were dispatched to a North Oak Street residence around 8:44 a.m. on a Monday, responding to a 911 call for an ambulance concerning a woman who was not breathing.

Inside the home, officers discovered Castle unconscious. She was transported to a nearby hospital, where medical personnel later pronounced her deceased.

Law enforcement officials stated that Horner was arrested at the scene and subsequently charged with second-degree murder.

According to court records, Horner is slated to appear again in Nassau District Court in Mineola on Thursday morning.

Victim's Background and Tributes

Information available on Castle's social media profile indicated she was pursuing a Ph.D. at Stony Brook University and also served as a research assistant at the institution.

Less than three years prior to her passing, Castle had posted a warm message on social media celebrating her sister's marriage to Horner. Accompanying a wedding photograph, Castle wrote:

My sister, my person, my partner in chaos, is now married to one of the most wonderful people in the world. I love you both forever!

School District Response

Horner is employed as a music teacher within the Oceanside School District. Following his arrest, the district announced that he had been placed on administrative leave.

Dr. Phyllis Harrington, the district's Superintendent, released a statement acknowledging the gravity of the situation:

We understand that this news is deeply disturbing.

District officials further stated that authorities in Nassau County had informed them the allegations "have no connection to the school district or its students."

The district's statement continued:

This staff member has been placed on administrative leave effective immediately, pending further review. The Oceanside School District is committed to maintaining a safe, professional, and trustworthy environment for our students, staff, and community. We stand by that commitment at all times.

Defense Statement and Legal Outlook

Gregory Grizopoulos, Horner's attorney, recognized the grave nature of the accusations but cautioned against premature judgment. Speaking to News12 Long Island, Grizopoulos stated:

These are very serious and disturbing allegations, and there's a very stark contrast between the allegations and his beloved reputation that he had as a teacher, with both his students and his fellow teachers. His family is devastated by the loss of their family member, Victoria, as well as the allegations against their son, Joe. We'll continue to evaluate the evidence as more details are disclosed to us.

Should Horner be convicted of second-degree murder, he faces a potential sentence of 25 years to life in state prison.

Joseph HornerVictoria Castlemurder chargeNew YorkNassau Countymusic teacheralleged obsessionNorth Massapequa