Music teacher asked sister-in-law for help moving a piano while his wife was out of town, and then strangled her: Police

Background: News footage of Joseph Horner (in blue) being escorted to court on June 30 (WNBC). Inset: Victoria Castle (Instagram).

A New York man who worked as a music teacher at an elementary school has been charged with the murder of his sister-in-law.

Joseph Horner, 27, is being held without bond after prosecutors said he strangled his sister-in-law, 25-year-old Victoria Castle. The Nassau County Police Department said in a press release that officers responded to a home in North Massapequa, New York, at 8:44 a.m. on Monday after receiving a call about an unresponsive woman. When they arrived at the home, they found Castle and transported her to the hospital, where she was pronounced dead.

Prosecutors said Horner, who placed the 911 call himself, was waiting for officers on the front porch of the home.

Local NBC affiliate WNBC was in the courtroom for Horner's arraignment on Tuesday, when he pleaded not guilty to intentional murder. Prosecutors said that before Horner called 911 to report that Castle was not breathing, he allegedly strangled her and sexually assaulted her after she was unconscious. According to WNBC's reporting, Horner and Castle lived in the same multifamily house in adjoining apartments. Horner is married to Castle's sister.

Prosecutors said that after Horner allegedly assaulted Castle, he changed his clothes, called 911, and waited for police to arrive on the stoop. Horner allegedly told police that he lured Castle to his apartment by telling her he needed help moving a piano. After she came upstairs to his apartment, he came up behind her and allegedly held her in a chokehold until she went limp.

According to prosecutors, Horner told police that he had been interested in Castle since 2017, a year after he met her sister. Horner said that his wife, whom he married three years ago, was out of town at a bachelorette party on the day he allegedly killed Castle.

More from Law&Crime: 'Humiliated' husband killed wife after learning 'she and her friends made fun of him,' strangled victim to 'shut her up'

Horner was employed as a music teacher in the Oceanside School District. In a statement provided to local ABC affiliate WABC, a spokesperson from the district said Horner had been "placed on administrative leave effective immediately, pending further review. We have no further information at this time."

Horner is due back in court on July 2.