The information at Killer Central.com is broadly limited to people who killed multiple times. In order to have an entry on the site they will have killed two or more people. Most will have been convicted of at least two murders (or manslaughters in some cases) and most will have killed three or more. In some cases our subjects have either admitted or be suspected of more murders than those for which they were convicted.

In some cases, where the actual murderer remains unknown, we have used their familiar ‘nickname’ such as “Jack the Ripper“, “The Bochum Serial Sex Murderer” or “The New York Strangler”

Broadly, our subjects fall into three categories, Serial Killers, Spree Killers and Mass Murderers, definitions of which you can see below.

The term “Serial Killer” was probably first used by Robert Ressler and FBI agent early adopter of the use of ‘psychological profiling’, a process by which law enforcement agencies could get a handle on the type of person responsible for a murder (or other serious crime).

Ressler was lecturing to a British police college in 1974 when he heard a description of some crimes occurring in series, such as rapes, burglaries and robberies.

Ressler figured that some killers were in a cycle of repeating their crimes due to increased tension and desire to commit the perfect murder, each one better than the last in an unending cycle or series. He coined the term ‘serial murder’ which has become more commonly used as serial killer.
There have been various definitions of serial killer but the most common features between all is that the murders would be multiple, usually three or more, and must be separated by time and location. So there should be some element of a ‘cooling off’ period between murders. This period is usually accepted as a month but can be weeks, months or even years between murders.

The FBI updated their definition of serial murder as:

The unlawful killing of two or more victims by the same offender(s), in separate events.

Spree killers differ from serial killers in that their killings occur around the same time and may be separated by location. Whereas a serial killer may have gaps of weeks, months or years between kills, a spree killer will kill his victims on the same day.
Derrick Bird is an example of a spree killer. He went on a ‘rampage’ in 2010 when he killed his brother and then took to his car to go to different locations around Cumbria in the UK where he shot and killed both people he knew and random strangers. He killed himself before police could arrest him.

Mass murderers kill multiple victims in the same event. Cases of terrorism can fall into the class orf mass murder where, for instance, a perpetrator blows up a bus full of people or causes the death of a plane full of passengers. In many cases the mass murder involves the suicide of the offender.