The benefits of DNA in the detection of crime

Report: 9
Meeting: Metropolitan Police Authority
Date: 14 September 2000
By: Commissioner

Summary

This report outlines:

• the benefit of DNA in the detection of crime;
• the substantial increase of profile to crime stain matches;
• how the MPS intend to optimise the forensic opportunity of DNA;
• how the MPS are continuing to work closely with the Forensic Science Service;

Supporting data and graphs are contained in the appendices.

A. Supporting information

National DNA Database

1. The National DNA Database was launched in the United Kingdom in April 1995. It was the first DNA database in the world to provide intelligence information to police. The database provides three different types of intelligence:

• a match between one individual and an unsolved crime stain, indicating a possible association;
• a match between one unsolved crime stain and another, potentially linking crimes;
• and the database can assist in confirm a person’s identity in much the same way as fingerprints, although with less certainty.

The police service under the guidance of ACPO established a DNA database. Part of the unique DNA profile of a person convicted of a criminal offence can be gathered and maintained on a database so that profiling from material containing DNA found at crime scenes can be compared against those profiles, identifying potential suspects for that crime.

Crime investigation

2. When looking at the value of DNA in the investigative process, it is appropriate to start with what we mean by “investigation” in a policing context. Simplistically, investigation is the process of finding out the true facts of an incident or occurrence in order to ascertain if any crime has been committed and who committed it.

The aim is to piece together the evidence of fact and present this, on behalf of the victim, to a court or other disposal process. The outcome sought is to disrupt or deter the offender and future potential offenders from committing further crimes.

The investigative process is a team effort. It starts from the initial receipt of an allegation or a call from a member of the public. The process then includes:

• control rooms staff;
• the uniform response officers;
• forensic officers;
• detectives;
• Criminal Justice Units;
• Crown Prosecution Service;
• the Courts and the diversion schemes such as youth offender teams;
• and drug rehabilitation.

One of the critical success factors of an investigation is the speed by which the offender is identified as a suspect. The quicker we can achieve this then the greater the opportunity to find corroborative evidence linking them to that crime scene or to that incident. This is because all evidence, whether physical or cognitive degrades with time.

As it stands, DNA profiling is not irrefutable, and current case law dictates that there should be supporting evidence. Police have an obligation to gain sufficient evidence to ensure the correct person is prosecuted. The likelihood of finding supporting evidence is enhanced by early results from forensic opportunity.

DNA - an investigative tool

3. So where does DNA fit in? One of the key opportunities in the investigation of a crime is the crime scene. This is true of both major and volume crimes. The principle underpinning scene examination is that every contact leaves a trace however small. The challenge to the Scientific Support Community is, how can they take advantage of this fact by utilising what are often very minute traces of evidence left at crime scenes by the perpetrator. Advancements in DNA technology have enabled trace evidence to be maximised by retrieving DNA rich material.

DNA is the means by which our genetic code is carried. It is based on our inherited characteristics from family members. Effectively we, as individuals, are unique and our DNA enables us to identify the unique characteristics of an individual from cells that are shed or left behind at crime scenes. The research has developed to such an extent that now the discrimination power for that process, at a ratio of 1 in a number of billions, is such that it is highly unlikely to be somebody other than the person identified.

Advancements in DNA

4. The technology started with the development of blood but has rapidly progressed such that DNA can now be obtained from cells left on cigarette ends, from the licking of envelopes, from hair, and from scrapings of skin left behind where entry has been forced or cowlings of vehicles have been attacked. These scrapings can be minute. A profile has been obtained from a kiss on the neck. This was gathered by swabbing the victim. The cells found were then grown to enable a profile to be obtained and compared against the database.

MPS policy development

5. The MPS has supported the enhanced development of the DNA database. Since November 1999 the MPS have been taking DNA from all suspects charged or reported for a recordable offence.

DNA samples taken since 1996/7

Forensic opportunity

6. A key skill of the scenes of crime officer is to seek out those areas where offender’s cells may be left, cigarette ends that are foreign to scenes and the blood that may have been spilt during an incident or offence. These stains are gathered and despatched to the Forensic Science Service. ‘Under the Microscope’ - HMI Thematic Review The following six forces were chosen for inspection to ensure a wide geographic and demographic spread - Kent Constabulary, Devon and Cornwall Constabulary, Northumbria Police, South Wales Police, North Yorkshire Constabulary, West Midlands Police.

This review of the use of Forensic products within the police service identifies that often we have not maximised the opportunity that the DNA identification can give to an investigation. This is especially true of volume crime. One of the reasons for this is the time taken for the processing of crime stains from the scene examination to the identification. This often takes several weeks.

Another interesting finding from this review is that the collection rates from Crime Scenes for DNA and fingerprints remain constant whether you have scene assessment or not. Scene assessment is where a police officer attends and makes a judgement as to whether there would be any likelihood of forensic evidence being found. Forces employing scene assessment obtain the same collection rates from crime scenes attended as those forces whose scene examiners attend all crime scenes. The quicker you can identify the offender as a suspect, the more chance you have of gathering that vital corroborative evidence sufficient to prove a case in court.

The benefits of DNA evidence were adversely affected by the slow processes within the MPS and Forensic Science Service. The MPS has developed a new scientific support strategy, which is currently in the process of implementation. Its aim is that all DNA identifications should be obtained within 5 days of the crime stain being gathered at the scene of a crime. This has been negotiated with the Forensic Science Service and will commence from November of this year. This significantly increases the likelihood of successful outcomes to our investigations where DNA is found at a crime scene.

Linking crimes

7. Another key element in relation to the use of DNA, as with all crime scene technologies such as footmarks, toolmarks and fingerprint identification, is the ability for us to link crime scenes. Crime scenes can be linked by the modus operandi of the offender, physical evidence left behind at a crime scene, or the tool used to force an entry etc. This enables us to identify who the serial offenders are within London. When we identify an offender through DNA or fingermarks, we not only question that person about the circumstances of that particular offence but also those other offences that we feel they may have committed. Additionally, when the arrest is conducted, the officers can search for the shoes and the tools involved together with property from those other crime scenes.

Improving forensic opportunity

8. This is therefore good evidence that the Metropolitan Police Service should be endeavouring to have all priority crime scenes attended by a scene examiner. Scene examiners are a cost-effective way of identifying offenders quickly. Early identification of suspects by DNA evidence may divert offenders from criminal opportunity through the involvement of :

• youth offending teams;
• restorative justice models;
• drug rehabilitation programmes.

The effect of these measures will be to deter, disrupt or divert offenders from pursuing criminal careers in London and thereby reducing crime.

The success story

9. Through increased harvesting of DNA and speedier turn around times, the Metropolitan Police Service has achieved a 183% increase in the number of identifications for the first quarter of this financial year in comparison to the same period last year. This offers us a great opportunity to increase judicial disposals against volume crime targets. Operation Intruder Since April all blood samples retrieved at a crime scene are taken by hand to the FSS at Lambeth on Mondays and Thursdays. The FSS then provide the result in 5 days. As mentioned above this is the forerunner to having all DNA results within 5 days. Eighty percent of these samples provide a profile, and forty six percent provide a match against the database.

B. Recommendations

1. Members note the report on the steps already taken by the MPS to harvest the benefits of DNA and the planned future initiatives.

C. Financial implications

The increased number of DNA and forensic submissions has required additional funding. The MPS budget allocation for 2000/01 is £25,500,000 (inclusive of a Home Office grant of £3,600,000) as compared to £16,800,000 for 1999/2000. The forecast outturn for the new scientific support strategy in the current financial year indicates that there will be a marginal overspend, but this will be more than offset by compensatory savings elsewhere in the MPS budgets.

D. Review arrangements

Members may wish to review the progress of the initiatives in a year’s time

E. Background papers

The following is a statutory list of background papers (under the Local government Act 1972 S100 D) which disclose facts or matters on which the report is based and which have been relied on to a material extent in preparing this report. They are available on request either the contact officer listed below or to the Clerk of the Police Authority indicated on the agenda.

None.

F. Contact details

The author of this report is Commander Godwin.

For information contact:

MPA general: 020 7202 0202
Media enquiries: 020 7202 0217/18

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