The number of officers feloniously killed on duty fell by about a third in 2012 when compared to the prior year, the FBI announced Monday.

Preliminary data shows that 47 officers were killed in 2012, a 35-percent drop from the 72 killed in 2011. The data will be included in the  Law Enforcement Officers Killed and Assaulted (LEOKA) report that's usually released in October. The report doesn't include officers killed in accidental deaths such as police vehicle accidents.

Of the 47 officers killed by suspects, 22 were killed in the South, eight were killed in the West, six were killed in the Northeast, five were killed in the Midwest, and six were killed in Puerto Rico or the Virgin Islands.

The profile of the slain officers mirrored earlier years in that the bulk (43 of the 47) were firearm-related. Of these, handguns led the way with 30, followed by rifles (seven) and shotguns (three). Non-gun deaths came from vehicles, a knife, and personal weapons (hands, fists, or feet).

The leading circumstance of the deaths (12) came as officers investigated suspicious persons or situations. Eight died conducting traffic pursuits or stops. Five were killed in ambushes. Four deaths cam on disturbance calls and three fallen officers were transporting, handling, or maintaining custody of prisoners. Other circumstances included drug-related matters, investigative activities, robberies in progress, a burglary in progress, and handling a mentally ill person.

In a troubling revelation, only 20 of the slain officers (42 percent) were wearing body armor at the time of their deaths. Only six of the officers fired their service weapons.

Of the 47 victim officers, 42 have been cleared by arrest or exceptional means.

An additional 45 officers were accidentally killed in the line of duty in 2012, a drop from the 53 accidentally killed in 2011. Of those, 22 died due to automobile accidents, 10 were struck by vehicles, and six officers were in motorcycle accidents. Three of the officers were killed in aircraft accidents, two in accidental shootings, one from a fall, and one officer died as a result of an ATV accident.

Final statistics and complete details will be published by the FBI in the fall.