Criminal Investigation

In the previous lecture I talked about policing in general. Among the things  I stressed were:

• The investigation of crime was only one of a number of activities in which the police are involved.

• The police have a great deal of discretion as regards the way in which they intervene in or handle a particular situation

• The police are a large organisation and to a large extent a subculture with their distinct values and attitudes, loyalties to one another and general suspicion of outsiders. This 'occupational culture' has its effect on the way policing works

In this lecture I will focus on criminal investigation, reconnecting with our journey through the chain of institutions which make up the criminal justice system.

Police as Filter

The police, as the first agency in the criminal justice process, are also of course the first agency to 'filter out' cases which although considered important enough by the public to report, are not considered so by the police. This is the first stage in a process of 'attrition' or leakage of offences out of the criminal justice process at various stages. In minor offences the police are themselves able to issue a caution to the suspect which to some extent puts the police in the position of being a mini-criminal justice system all on their own. On the other hand police decisions to 'no-crime' (not to record the reported incident) or to take 'no further action' on a reported offence have, over recent years, come in for a good deal of criticism particularly from those concerned with issues such as rape and domestic violence or racially motivated attacks. This is often seen as a failure on the part of the police to take these issues seriously. Police would claim that they have done much in recent years to take on board the criticism and to remedy it.

Serious crimes acted upon by the police (such as murder, armed robbery, violence) immediately involve specialist investigators known as detectives. In the UK detectives work for the Criminal Investigation Departments (CID) of police forces.

The nature of detective work

The London Metropolitan Police detective branch was set up in 1842 (the Met itself was founded in 1829), The Criminal Investigation Department in its present form dates from 1877 but was virtually a separate organisation from the rest of the police up to the early 1970s. There is something of a mythology surrounding detective skills and crafts. Brilliant intuitions and deductions are the stuff of crime thrillers. But most of the great detectives of English crime fiction in the early years of the twentieth century were amateur sleuths (Sherlock Holmes) and foreigners (Agatha Christie's Inspector Poirot). Police detectives didn't have much of a reputation. 

'self solving' crimes

Some crimes are more difficult to solve than others. Certain types of serious crimes virtually solve themselves. There is, for example, a very high clearup rate for homicides. In England and Wales there are about 700 murders per year and a clearup rate of  around 88% . The reason is that most cases are 'self-solvers' (see Innes 2002) in that the killer is known to the victim and detectives can expect to get a 'lead' in a relatively short time. This is the case for example where the attacker was seen at or near the scene of the crime or was the last person to see the victim. Detective work such as forensic examination, interviewing the suspect and other people who knew the victim and the killer is essentially the gathering of corroborative evidence to back up a case in which the Prime Suspect is rapidly decided. Where the attacker is not immediately known the investigation process will start with the close associates of the victim and work outwards in the direction of friends and associates and attempt, by process of elimination, to establish a motive.Then, even if the individual confesses when confronted, there is a need for corroborating evidence such as forensic evidence (DNA, fingerprints) or witnesses who say they saw the suspect near the crime scene at the appropriate times etc.

In other cases such as an armed robbery, detectives from the robbery squad may be familiar with the techniques of various offenders well known to them regarding techniques of safe-breaking, entering buildings, use of certain types of firearms etc.  They may get a good idea from the details of evidence at the scene of crime as to who was the likely offender. A recent study by Roger Matthews of Middlesex University (2002) of the policing of armed robbery confirmed the importance of witness identifications in leading to clearups. The typical robbery investigation starts with witness identification of known suspects who are then pursued. The police may also get information from various members of the criminal underworld with whom they have regular contact. There is often the possibility of a trade off. 'We could pull you in for such and such a robbery but if you give us some information about who was involved in  the robbery we are now interested in, we might press for leniency when your particular case comes to court.'

the role of the public

In very many cases however, there is no obvious suspect. In such cases the role of the public is absolutely central in solving the crime. In fact the vaste majority of crimes can be said to be solved by evidence from the public: victims or witnesses who report their evidence to the police. Studies, both in the UK and the USA during the 1970s and 80s of the productivity of detectives found that most cases were solved on the basis of eye-witness statements if at all and of additional detective work was of low productivity (Greenwood 1977). Steer (1980) found that it was mainly members of the public who identify culprits. Only in 10% of the cases he studied was the suspect identified as a result of police investigation while 40% of defendants were directly identified by members of public. 

You may be familiar with police appeals to the public to come forward with evidence. For crimes which take place in public places large yellow boards (in England) will be placed in the street near the scene of the crime with details of the incident and a telephone number where members of the public an contact the police in confidence. People may be stopped in the street and asked by police officers whether they can remember anything suspicious happening in that area around that time a few days ago. The police may even stage a reconstruction of certain aspects of a crime. For instance in a case of abduction and murder of young people the police may employ actors to replay the last known sighting of the victims in the hope that this might help bystanders remember suspicious events or details which they had since forgotten.Another angle is illustrated by homicide investigations. There is a very high clearup rate for homicides. In England and Wales there are about 700 murders per year and a clearup rate of  around 88% . The reason is that most cases are 'self-solvers' (see Innes 2002) in that the killer is known to the victim and detectives can expect to get a 'lead' in a relatively short time. This is the case for example where the attacker was seen at or near the scene of the crime or was the last person to see the victim. Detective work such as forensic examination, interviewing the suspect and other people who knew the victim and the killer is essentially the gathering of corroborative evidence to back up a case in which the Prime Suspect is rapidly decided. Where the attacker is not immediately known the investigation process will start with the close associates of the victim and work outwards in the direction of friends and associates and attempt, by process of elimination, to establish a motive.

In this respect good relations between police and local communities pay off. If the police are well liked and regarded as doing a useful job then people will be more forthcoming about things they have seen  or remembered than if they police are disliked in the area.

particular publics

The victim of crime may of course be a member of a particular subculture or profession. In such cases the police may  need to work very closely with other members of that group in order to get information leading to the identification of a suspect. Murders of prostitutes are a particular example.  The police need to establish trust with working girls in order to get information, in particular to establish the identities of regular clients. This was of particular importance in the murder of five prostitutes in Ipswitch in December 2006. (see box below)

We have already mentioned another particular subgroup whom the police may rely on for information about particular crimes: members of the organised criminal underworld. Dick Hobbs (1988) in his study of the relation between detectives and villains in the old East End of London describes relatively closed communities in which criminal families were well known, had a certain amount of power and even respect in their communities and in which gaining information meant moving within the criminal underworld and doing deals with one set of villains to secure information leading to the conviction of others.

Here the informant from within the criminal underworld had a special position. The 1970s was the high point of the use of informants by detectives. The informant, known popularly as the 'supergrass' was generally a bona fide gangster who turned state evidence in return for immunity from prosecution, or conviction on a lesser charge. The modern system of undercover informants (see below) differs in a number of respects.

The problems with the use of supergrass informants were obvious: serious villains were being allowed to get away with major crimes in return for giving evidence. As Hobbs remarks, at the trial of the notorious Kray twins in 1969 the various individuals in the witness box had committed crimes at least as serious as those being sent down! Also the motives of supergrasses were not beyond question. Revenge, the elimination of competition in the criminal underworld could all be motives. The evidence of supergrasses could not be seen as necessarily reliable.

Another occupational hazard of too close a relationship with gangsters is of course police corruption . What may start out as a compromise in order to get information turns into detectives colluding with the commission of offences. In London these matters came to a head in the early 1970s when a number of detectives were dismissed and Sir Robert Mark, the Commissioner of the Metropolitan Police placed CID firmly under the central control of the uniformed branch of the police.

Other types of crime may post particular problems police investigators.  Complex fraud cases in the City of London, in order to be detected, may require the investigators to master all the skills of accountancy and banking. Such skills are certainly beyond the reach of the average detective. In 1986 the UK government established the Serious Fraud Office a special group consisting of a mixture of detectives, accountants and lawyers, to investigate and prosecute the most serious financial frauds in England and Wales.

Meanwhile technologic advances in forensic science (such as the use of DNA samples), or the growth of public surveillance systems such as Closed Circuit Television (CCTV) may be of help in gathering evidence

Obstacles to effective investigation

Various things may get in the way of effective police investigation which may be of the police's own doing. That is to say characteristics of the police themselves rather than difficulties in finding evidence. An obvious obstacle is racism. This was mentioned in the lecture on police organisation.. The most important case in recent times in the UK is the case of the murder of Stephen Lawrence. The Macpherson Report into the conduct of the police details how police racist stereotypes obstructed effective investigation, for example by treating a key witness as a suspect simply because of his ethnicity. The other issue raised by the report was the issue of police corruption. The young white men suspected of murdering Lawrence included the sons of some local criminals. Macpherson dealt with allegations that there was collusion between some police officers and these criminals to obstruct the investigation. In this case corruption was used to delay and obstruct the investigation. Corrupt practices can also be used to speed up an investigation. We shall deal with this in a moment. 

getting a result

There is a lot of pressure, particularly in a case with a high public profile, on detectives to quickly identify a suspect.  Daily press conferences, answering awkward questions from journalists as to the progress of the investigation may be regarded by detectives as a diversion from the business of solving the crime. But the public has a right to know what is happening and indeed the pressure to get a result as quickly as possible is the normal way that detectives work.  Once the evidence, from the public, witnesses, forensic details, starts to be assembled the investigators are anxious to identify a 'lead': someone they can start to focus on as a possible suspect. In the words of criminologist David Bayley (1994) in his international survey of policing methods:

"Contrary to their fictional portrayal, detectives quickly formulate a theory about who committed the crime and then set about collecting evidence that will support arrest and prosecution... in short, criminal investigators begin with an identification, then collect the evidence; they rarely collect the evidence and then make an identification." (Bayley 1994 quoted in Matthews 2002: 107)

The danger is of course that once evidence begins to point in the direction of a particular suspect, there may be other evidence that conflicts with this. There may be a tendency to ignore or downplay such evidence, not from bad intent but because the evidence clashes with a promising hypothesis that looks like leading to a 'result'.  A key question. paticularly from the standpoint of prosecution, (taking the case to court) is what checks and balances there are on any tendency by the investigators to rush to conclusions and ignore evidence which conflicts with, or  fails to corroborate their line of inquiry.

Under the French and similar jurisdictions in other parts of the European Union the  investigators work, once the crime has been reported to the police, under the supervision of a judge. Known as the juge d'instruction (loosely translated as 'investigating judge') this legal official has overall charge of the investigation. In his book Presumed Guilty the well known English Barrister Mike Mansfield (1992) took a French investigating magistrate through an English case from police investigation to court trial. At each stage she explained how differently the procedures were in France. Thus while detectives might get enthusiastic about leads and 'hunches' the judge had to avoid all this. As she explained to Mansfield:

"The principles on which I operate are essentially to be free from all external pressures, to have no ideas and no hunches, to be totally practical and know nothing about anyone. My whole intention is not to be prejudiced, not to come to a case with preconceptions and above all to protect the rights of the people." (Mansfield 1992: 54)

In this system all the evidence, however trivial it may or may not seem, will end up in a single large document, the dossier, which is produced by the investigating judge and is equally available to defence and prosecution.

We don't have time for any systematic comparison of the French and English systems but it has to be said that the absence of anyone resembling an examining judge at the state of criminal investigation does remove an important check on investigations going off the rails. Supervision of criminal investigation is only by other, more senior, police officers.  The present system in the Uk is to rely on a Senior Investigating Officer (SIO) to review the way the inquiry is proceeding and perhaps to stand back and ask questions about why it has gone in a particular direction. There is also the possibility of external review of the progress of the investigation by officers from another force (UK police forces are regional, there is no single national police organisation). Finally, as in other jurisdictions the involvement of the public prosecutor in the conduct of the investigation  may act as a brake on police coming too readily to conclusions.

But in England and Wales these are relatively recent developments. They may be seen as responses to the crisis of the 'old regime' of police investigations which came to a dramatic end in the 1980s. and was seen by critics as a system out of control in which detectives worked implicitly on the maxim "a little bit of evidence makes you a little bit guilty" and some evidence against you (such as being near the scene of the crime and perhaps having been under suspicion for similar offences before) could find you in the police station being persuaded to admit to the offence under investigation. At that stage all the stops were pulled out to secure a confession.

Under such a system an early arrest was particularly important precisely because it is a coercive measure that gets the suspect on police territory, which is a somewhat intimidating experience, and thus the suspect is more likely to confess to the crime.  There was indeed much evidence of coercion  For example a study conducted in the early 1980's  (Walkley 1987) based on interviews with 100 detectives found 43 agreeing with the statement ' it is sometimes helpful to slap a suspect across the face.' But the most important evidence that something was wrong with police investigations were a number of high profile convictions later overturned as 'unsafe.'

By the 1970s and 1980s it was clear that the legitimacy of the criminal justice system was at stake in two key areas of police corruption and unsafe convictions. It was the latter which became the focus of policy making. Following the Confait case the Royal Commission on Criminal Procedure was set up (in 1978) and reported in 1981. Some of its main recommendations were carried out in two pieces of legislation

• Prosecution of Offenders Act 1985 which established a separate Crown Prosecution Service (CPS) We shall deal with this in the next lecture  

• Police and Criminal Evidence Act 1984 which came into force in 1986

1980s: defending suspects rights

Both these pieces of legislation were influenced to a considerable extent by the need to prevent miscarriages of justice such as had transpired in the Confait case. The establishment of the Crown Prosecution Service, while in no sense a form of independent judicial supervision of police investigations on the French model noted above, and not having even the powers of the Scottish Procurator Fiscal or the District Attorney in the US was nevertheless conceived of as some sort of check on police construction of cases by filtering out those which would not stand up in court or for which evidence was substantially lacking.

The 1984 Police and Criminal Evidence Act, while strengthening police powers in a number of respects introduced the principle of recording of police actions. In the Codes of Practice for police issued as the Act went into effect

• street stops and searches by uniformed officers were to be recorded and a copy of the record, specifying the reasons for the stop, given to the person stopped. 

• police interviews with suspects to be tape recorded. Courts can reject evidence based on confession if it is seen to be taken under duress or if would jeopardise a fair trial. (In Scotland, it should be noted, evidence based on confession alone is not admissible but self-corroboration. This is also the case in France. It was not seen appropriate to bring this principle firmly into English law) The hope was, nevertheless that this would bring to an end the type of case illustrated by Confait. Ideally, detectives would abandon the pressured interview: "you did it didn't you- go on admit it!" in favour of a more free recall approach. "Tell us what happened then?"

However, how effective they have been is another matter. In the case of stop and search, a full 16 years after the PACE regulations came into force Home Office researchers found that only a third of such stops were being actually recorded  (see Bland et al 2000).

As regards police interviews a few years after PACE, Mike McConville and his colleagues (McConville, et al. 1991) suggested that little had changed in terms of police interviews especially as regards police 'interrogative suggestibility'. In other words the recording of interviews had not altered the power relations of the whole interview process and the fact that "Interrogation takes place in an environment which increases the vulnerability of the suspect and maximises the authority and control of the police" (page 78) Although the impact may well be uneven, the fact that the Courts can reject confession evidence if not properly produced, may have had an effect on police culture.

1990s: Efficiency and Effectiveness

1989 and 1991 saw the overturning of the Guildford and Birmingham IRA convictions. This led to a further Royal Commission on Criminal Justice which reported in 1993. The remit of the Commission was wide and covered all aspects of the criminal justice process. As far as police investigations were concerned the Commission's recommendations were not particularly far reaching. Again, the recommendation was that confessions (unlike in Scotland) did not require supporting evidence but that police investigations should not be closed down once a confession is made. Interviewing training should be given to police officers. Videotaping of police custody suites and tape recording of witness statements were recommended.

But the political atmosphere was changing. If key legislation of the 1980s such as PACE and the setting up of the CPS had been to a considerable extent informed by a desire to prevent miscarriages of justice, by the 1990s the theme of efficiency and effectiveness in the control of crime and the conviction of offenders was in full swing. Two pieces of legislation in 1994 illustrate this shift. (though the 1990s have seen a large volume of reports, White Papers on police reform and other legislation)

The Criminal Justice and Public Order Act 1994 severely modified the right to silence by allowing court to draw inferences from a defendant's failure to answer police questions. The Royal Commission had in fact defended the right to silence. The modification of this rule marks a decisive shift away from a due process in the direction of effective control of crime. The aim is to speed up the conviction of offenders rather than guarantee the rights of the defendant.

general police performance indicators

During the period of the Conservative governments from 1979 to 1997 the notion that public services were bloated bureaucracies in need of a dose of the competitive efficiency of the private sector gained ground. Hitherto such arguments had not been applied to the criminal justice system but this was no longer the case. The concern with rising crime and falling clearup rates made this a popular theme. The Labour governments since 1997 have continued this trend.. No-one has quite suggested that the police would have to compete with, say, private security firms to secure contracts! Rather the idea was to introduce notions of 'value for money' or 'best value' into police work.

In 1993 the government published a White Paper on Police Reform and followed this with the Police and Magistrates Courts Act 1994. This is the second piece of legislation of that year which illustrates the shift from due process to efficiency and effective crime control. This Act, besides introducing a number of changes in the local governance of police via Police Authorities which traditionally include elected members of local government, enables the Home Secretary to set performance targets for police forces within which local policing plans have to work. This Act was rapidly followed by a consolidation of efficiency and performance oriented measures such as the 1995 Review of Police Core and Ancillary Tasks by Her Majesty's Inspectorate of Constabulary. The HMIC, rather like school inspectors would visit and inspect the efficiency of police forces. The 1995 review urged a refocus of police on key aspects of crime control. At the same time other bodies associated with an orientation to efficiency such as the government's Audit Commission started taking an interest in the police and reporting on efficiency. We shall see the specific role of the Audit Commission in relation to the work of detectives presently. Finally, the White Paper of 2001 Policing a New Century: A Blueprint for Reform was followed by the Police Reform Act 2002 which, again from the standpoint of efficiency and concentration on core tasks, inaugurated an Annual Policing Plan and also created the post of auxiliary Police Community Support Officers (PCSOs) to take over some of routine patrolling and also. (in July 2004 the government proposed a further increase in the number of PCSOs as part of the drive against anti-social behaviour (see lecture on crime prevention)

We have moved rather from the specific issue of criminal investigation to give a flavour of the wider changes governing policing since the beginning of the 1990s. Before moving back to focus on the work of detectives it is useful to briefly look at some more general issues raised by the new managerialism and orientation to efficiency. There are two basic issues:

how is the efficiency of a police force to be measured?

It is notoriously difficult to measure the efficiency of something like a police force. This is a common problem across the public services. Thus if something like arrest rates are used as an indicator of efficiency, any police force can appear to be more efficient just by going out and arresting more people, many for trivial crimes. If the 'clearup' rate is used (percentage of reported crimes for which someone is arrested) then this may be artificially inflated by getting criminals to 'take into consideration' more offences of a similar nature to the one for which they are arrested, or by reclassifying certain reported crimes (e.g. from burglary to criminal damage). There are similar problems across the public sector For example, if the supposed efficiency of a University were to be measured by the amount of first class honours degrees awarded then it would be a very simple matter for academic staff to ensure that more such degrees were awarded. There would be a strong pressure in the direction of 'grade inflation.' Likewise if the efficiency of hospitals is to be measured by the length of waiting lists then there are various ways of shortening them such as concentrating on quick turnaround operations and ignoring the serious ones which require a long bed stopover. The general point is that it is difficult to use as an indicator of efficiency an activity which can be easily changed and manipulated by the organisation whose efficiency is being measured. A better measure might be annual local surveys of residents of how well they think the police are performing. But this brings us to the second issue: there may be a conflict between measures of efficiency and public priorities.

In 1996 the government Audit Commission produced a report entitled: Streetwise: Effective Police Patrol. This report criticised the effectiveness of some aspects of 'community policing' pointing out that putting more officers on foot patrol did not necessarily lead to increased clear ups for crime. The report suggested that police forces should make better use of intelligence information and focused surveillance of known offenders (we are moving back towards the work of detectives here) rather than patrolling the streets. Yet foot patrols are the most important demand that the public makes of the police and which are voiced in Community Safety Forums. Foot patrols make people feel safer even if they are not cost-effective. Reconciling these two is to some extent the aim of the new PCSOs. They have less than proper police training but are around to be seen and thus free up the police for more serious crime work. That is the idea.

detectives: proactive policing and the use of informants

So how has all this affected the work of detectives? One consequence has been, as with other branches of the police, a drift to national centralisation. As far as serious crime was concerned since 1964 there have been Regional Crime Squads which pool detectives from several police force areas to deal with serious organised crime. As the latter, in particular drugs trading, has become more serious the National Criminal Intelligence Service (NCIS) was set up in 1992 and the Police Act 1997 established a National Crime Squad. At the time of writing the government has announced this is to be amalgamated with NCIS to form a Serious and Organised Crime Agency. (SOCA) But details have yet to be spelled out.

Probably the most important efficiency document oriented to criminal investigation was an Audit Commission report of 1993: Helping With Enquiries: Tackling Crime Effectively. In the context of urging a re-emphasis on core tasks of prevention and detection of crime, it argued that police should spend less time on a reactive strategy of responding to reported incidents and more time in proactive targeting of known offenders. Policing should be Intelligence-led.  The Audit Commission was worried that rising crime (in fact crime rates have fallen somewhat in recent years) would overwhelm reactive policing. Police would spend all their time reacting to reported incidents and serious offenders would not be caught. There would eventually be a fall in public confidence. The Commission therefore advocated a shift in focus from targeting the crime (reactive) to targeting the offender (proactive) and as part of this a greater use of informants. The legality of using informants is now regulated under the Police Act 1997 and the The Regulation of Investigatory Powers Act 2000.

The Commission argued this was cost-effective. But recent research (Norris and Dunnighan 1999) challenged this on the basis that the Commission only calculated cost of paying informants vs. crimes cleared up and ignored overhead costs of police handlers, cost of initial approaches to lower level criminals that police need to 'turn around' as informants etc. The researchers also argued that these cost calculations  ignored wider political and social costs: crimes committed by informers not acted on so as not to break the relationship with or blow the cover of the informant, or the fact that informants may act in the manner of agent provacateur; setting up crimes to catch people. The whole pressure in this direction is that informants are only of use if they are actively engaged in the criminal subculture; and to retain their credibility in the criminal subculture they have to commit crimes. Also the civil liberties implications of informants engaging in unsupervised surveillance of innocent people are not considered. The whole strategy of 'targeting serious and prolific criminals' has civil liberties implications. The new informant differs from the old supergrass of the 1970s in that he or she is more likely to be a permanent undercover worker for a considerable period of time rather than an arrested person who decides to 'co-operate' in return for a lenient sentence. In my lecture on organised crime here there are some links to material on undercover informants.

Roger Matthews, in his study of armed robbery, challenges the distinction between proactive and reactive policing. Targetting of known offenders may, for example, give rise to information about new crimes which then have to be reacted to. Conversely, in reacting to crimes, detectives come across new suspects who then have to be place under surveillance. It is not an either-or situation. Matthews also point to a potential conflict between intelligence led policing and other performance indicators. He points out, in effect that organisations like the Audit Commission are making contradictory demands: on the one hand calling for intelligence-led proactive policing and, on the other, emphasising measures of performance such as clearup rates:

"It is paradoxically precisely because the police are placed under pressure from organisations like the Audit Commission and the Home Office to reach performance 'targets' and improve clearups that they gravitate towards those recorded crimes that are most easily detectable and maintain the emphasis on 'reactive' strategies. Targeting serious and prolific criminals, placing them under surveillance and gathering information can be an extremely time-consuming activity whose outcome is uncertain. It is often easier to achieve results by 'rounding up the usual suspects' once a robbery has been committed. (Matthews 2002: 111)

Also interesting is his argument that the nature of the particular crime of armed robbery is changing, that there is probably a decline in the number of professional robbers known to the police in favour of amateurs and novices dealing with soft targets such as off-licences, shops, petrol stations rather than banks and cash delivery vans. As firearms become easier to acquire, and as the old professional villain gives way to individuals moving opportunistically in and out of crime, the techniques of surveillance of known offenders becomes harder to sustain as something which yields useful intelligence. From this standpoint the new innovations which ,over the last few years have been heralded as new weapons of efficiency and effective policing, appear in a rather different light

references

Bayley, D. (1994) Police For The Future. New York: Oxford University Press
Baldwin, J. McConville, M. 1980. Confessions in Crown Court Trials London: The Stationary Office
Bland, N. et al. (2000) Upping the PACE? An evaluation of the recommendations of the Stephen Lawrence Inquiry on stops and searches. Home Office Police Research Paper 128. London: The Stationary Office
Greenwood, P. et al. (1977) The Criminal Investigation Process. Washington DC: Rand Corporation
Hobbs, D. (1988) Doing the Business. the Working Class and Detectives in the East End of London. Oxford University Press
Innes, M. (2002) The 'Process Structures' of Police Homicide Investigations. British Journal of Criminology  42: 669-688
Matthews, R. (2002) Armed Robbery. Cullompton: Willan Publishing
McConville, M. et al. (1991), The Case For The Prosecution: police suspects and the construction of criminality. London: Routledge
Dunningham, C and Norris, C. (1999) 'The Detective, the Snout and the Audit Commission: The Real Costs in Using Informants' Howard Journal of Criminal Justice 38:1 pp 67-86
Steer, D. (1980) Uncovering Crime. London: The Stationary Office
Walkley, J. (1987) Police Interrogation. London: Police Review Publishing Co.