RIVERHEAD, N.Y. (AP)  -- A New York City police instructor has admitted he shot and killed his fiancee, also an NYPD officer, inside their Long Island home in September 2007.
   
Alexis Chaparro pleaded guilty to first-degree manslaughter Wednesday in the death of Officer Sonia Garcia in state Supreme Court in Riverhead. Chaparro, originally indicted on second-degree murder charges, faces 10 years in prison when he is sentenced on Jan. 7.
   
Prosecutor Janet Albertson said recent appeals court decisions have made it difficult to convict suspects in one-on-one shootings like the killing of Garcia, so the decision was made to accept a plea deal to ensure Chaparro spends a ``substantial prison sentence.''
   
Chaparro contended he was concerned about burglars in his Bay Shore neighborhood and shot and killed the victim after being awakened from a sound sleep.

Newsday reports outside court Wednesday, Garcia's sister, Evelyn Hernandez, 26, of Park Slope in Brooklyn, said she now believed Garcia was killed for discovering Chaparro in the midst of a homosexual love affair.

"My sister walked in on him with another man and that's why she's dead," Hernandez said.