NEW ORLEANS (AP) - Jurors have heard opening statements in the trial of a man charged with first-degree murder in the 2015 shooting death of a New Orleans police officer.

  

The attorney for Travis Boys told jurors that Boys, who faces life in prison if convicted, is mentally ill.

  

Boys has pleaded not guilty and not guilty by reason of insanity in the death of Officer Daryle Holloway. New Orleans news outlets report that defense attorney Billy Sothern told jurors they will have to determine not what happened, but why it happened.

  

Assistant District Attorney Inga Petrovich said the evidence will point to a guilty verdict.

  

Holloway was shot to death while transporting Boys to jail in a police SUV. Police have said they believe Boys smuggled a gun into the vehicle.