After four years and three government investigations, Gov. Rick Scott of Florida has assigned a new special prosecutor to re-examine the circumstances surrounding the shooting death of a deputy sheriff’s girlfriend who was in the process of breaking up with him.

The death of Michelle O’Connell, 24, in September 2010 continues to stir strong emotions in northeast Florida and beyond in part because the local sheriff and medical examiner, after a flawed investigation, quickly concluded that she had killed herself with her boyfriend’s service weapon.

A subsequent investigation by the Florida Department of Law Enforcement, an independent state investigative agency, challenged the suicide ruling after, among other things, finding two neighbors who said they heard a woman crying for help before hearing shots. But no charges have been brought against the deputy, Jeremy Banks.

Last November, the case was the subject of a lengthy examination by The New York Times, in collaboration with the PBS investigative news program “Frontline.” That examination found serious shortcomings in the sheriff’s department’s handling of the case involving its own deputy, while also casting light on the problem of domestic violence involving police officers.