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Teacher Arrested After Allegedly Killing Then Sexually Assaulting Sister-in-Law He Was Obsessed With

US Weekly Published Jul 1, 2026 Reviewed Jul 4, 2026 ✓ Reviewed by citations.press editors
Teacher Arrested After Allegedly Killing Then Sexually Assaulting Sister-in-Law He Was Obsessed With
Joseph Horner, a 27-year-old music teacher in Oceanside, New York, was arrested and charged with second-degree murder in connection with the death of his sister-in-law Victoria Castle, who was 25 years old.
27 years · Joseph Horner25 years · Victoria Castle
Victoria Castle was a Ph.D. student in geosciences at Stony Brook University at the time of her death, according to Stony Brook University’s website.
Horner’s attorney Gregory Grizopoulos stated that Horner is a tenured music teacher who is “very well loved by his students and his colleagues.”
Joseph Horner, 27, and Victoria Castle, 25, lived in the same house that was split into two separate apartments.
27 · Joseph Horner25 · Victoria Castle WABC, news outlet
If convicted, Joseph Horner could face 25 years to life in prison.
25 years · Joseph Horner prosecutors, prosecutor
Joseph Horner pleaded not guilty to the charges during a court appearance on Monday, June 29.
NBC, news outlet
Joseph Horner admitted that he was attracted to Victoria Castle beginning in 2017.
2017 · Joseph Horner prosecutors, prosecutor
The Oceanside School District placed Joseph Horner on administrative leave effective immediately following his arrest, according to a district statement reported by WABC.

A teacher in Long Island was arrested after he allegedly strangled his sister-in-law to death before he sexually assaulted her, and prosecutors claimed that he was obsessed with the victim.

The Nassau County Police Department announced that Joseph Horner was arrested and charged with second-degree murder in connection with the death of a woman in Massapequa, New York.

The alleged victim was later identified as Horner’s sister-in-law, Victoria Castle, according to WNBC.

Horner, 27, and Castle, 25, lived in the same house that was split into two separate apartments, per WABC. Horner lived upstairs with his wife in the upstairs unit, while Castle lived downstairs.

News 12 reported that Horner’s wife was not home at the time of the incident and that she was out of town at a bachelorette party. However, further details about the trip have not been publicly shared.

Prosecutors claimed that Horner asked Castle to help him move a piano in his unit before he allegedly placed her in a chokehold and caused her body to go limp, according to all three outlets. He then allegedly sexually assaulted Castle.

Additionally, prosecutors claimed that Horner admitted that he was attracted to Castle beginning back in 2017.

It is not currently clear when Horner and Castle met or how long Horner has been married to his wife.

Following his arrest, Horner pleaded not guilty to the charges during a court appearance on Monday, June 29, according to NBC. He is currently being held in custody without bail. If he is convicted of the charges, Horner could face 25 years to life in prison.

He has since obtained an attorney, who insisted he is innocent.

“He’s an Oceanside teacher, he’s tenured, he’s very well loved by his students and his colleagues,” Horner’s attorney Gregory Grizopoulos said in a statement to WABC. “These allegations are not very in line with what his community, friends and family believe.”

In addition to confirming that Horner worked as a school music teacher at the school, WABC reported that Castle was a Ph.D. student at Stony Brook University. She was studying geosciences at the time of her death, according to the school’s website.

The Oceanside School District has released a statement following Horner’s arrest. “This staff member has been placed on administrative leave effective immediately, pending further review. We have no further information at this time,” the statement read in part, according to WABC.

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