UNIONDALE - The Nassau County Police Department has opened an internal investigation into whether the officer who opened fire on an armed home invasion suspect and accidentally hit a college student was justified in his actions.

Investigators say ex-con Dalton Smith, 30, had Hofstra University student Andrea Rebello in a headlock while he brandished a loaded gun during a home invasion near campus. When Smith allegedly pointed the gun at a police officer who was responding to the scene, the officer fired, hitting Smith seven times and hitting Rebello once. Smith and the 21-year-old student were killed.

The officer who fired the shots is a 12-year veteran of the Nassau County Police Department. Homicide Squad Lt. John Azzata says the officer made a split-second decision because he believed his and Rebello's lives were in danger.

Garden City attorney Amy Marion, who has previously represented police officers in deadly shootings but is not connected to this case, says there are other factors at play when deadly force is used.

"They're not allowed to use deadly physical force when that force presents a grave risk of danger to innocent individuals," Marion says. She says it's a difficult and challenging case, but she questions the officer's decision to walk inside the house knowing a gunman was inside with innocent victims.

Marion says it's the kind of situation that should have called for trained hostage negotiators.

Officials have said that the officer who fired the shots is now on sick leave. The Nassau County District Attorney's Office says it is monitoring the police departments's internal probe into the case, and notes that it "reviews the facts and circumstances of every police-involved shooting."