2. How is homicide defined and measured?

The term “homicide” covers the offences of murder, manslaughter and infanticide1. Murder and manslaughter are common law offences that have never been defined by statute, although they have been modified by statute. In this article, the manslaughter category includes the offence of corporate manslaughter, which was created by the Corporate Manslaughter and Corporate Homicide Act 2007, which came into force on 6 April 2008. The offence of infanticide was created by the Infanticide Act 1922 and refined by the Infanticide Act 1938 (section 1).

Data presented have been extracted from the Home Office Homicide Index, which contains detailed record-level information about each homicide recorded by police in England and Wales. It is continually updated with revised information from the police and the courts and, as such, is a richer source of data than the main recorded crime dataset2.

In accordance with the Statistics and Registration Service Act 2007, statistics based on the Home Office Homicide Index have been re-assessed against the Code of Practice for Official Statistics and found to meet the required standard for designation as National Statistics3. Further information on the interpretation of recorded crime data is provided in the User Guide.

Homicide Index data are based on the year when the offence was recorded as a crime, not when the offence took place or when the case was heard in court. While in the vast majority of cases the offence will be recorded in the same year as it took place, this is not always the case. Caution is therefore needed when looking at longer-term homicide trend figures. For example:

the 172 homicides attributed to Dr Harold Shipman as a result of Dame Janet Smith’s inquiry took place over a long period of time but were all recorded by the police during the year ending March 2003

the 96 deaths that occurred at Hillsborough in 1989 were recorded as manslaughters in the year ending March 2017 following the verdict of the Hillsborough Inquest in April 2016

Furthermore, where several people are killed by the same suspect, the number of homicides counted is the total number of victims killed rather than the number of incidents. For example, the victims of Derrick Bird are counted as 12 homicides rather than one incident in the year ending March 2011 data.

The data refer to the position as at 16 November 2017, when the Homicide Index database was “frozen” for the purpose of analysis4. The data will change as subsequent court hearings take place or as further information is received.

The circumstances surrounding a homicide may be complex and it can take time for cases to pass through the criminal justice system (CJS). Due to this, the percentage of homicides recorded in the year ending March 2017 (and, to a lesser extent, those recorded in earlier years) that have concluded at Crown Court is likely to show an increase when the next figures from the Homicide Index are published5. Conversely, the proportion of cases without suspects or with court proceedings pending is expected to decrease as police complete more investigations and as cases pass through the CJS (see “What do we know about suspects?” section for further details).

For the purposes of the Homicide Index, a suspect in a homicide case is defined as either:

a person who has been arrested in respect of an offence initially classified as homicide 6 and charged with homicide, including those who were subsequently convicted

a person who is suspected by the police of having committed the offence but is known to have died or committed suicide prior to arrest or being charged

Where there are multiple suspects in a homicide case they are categorised in the Homicide Index as either the principal suspect or a secondary suspect. There is only ever one principal suspect per homicide victim. If there is any conviction information available then the suspect with the longest sentence or most serious conviction is determined to be the principal suspect. In the absence of any court outcome, the principal suspect is either the person considered by the police to be the most involved in the homicide or the suspect with the closest relationship to the victim.

As more than one person can be convicted for a single homicide, the number of people convicted will not necessarily be the same as the number of victims recorded. However, if the outcome of only the principal suspect in each case is examined (that is, one suspect per victim), this can provide a more direct comparison to the case outcome of each homicide.

Notes for: How is homicide defined and measured?