Criminology3,376 views·Updated Jun 18, 2026·11 pages

Criminology Unit 3 AC 1.2: Comprehensive Review

Kashan Malik@kashanmalik

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Ever wondered how police catch criminals using everything from DNA...

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Forensic techniques:
'Forensics'- refers to the scientific techniques and tests used to assist in investigating crime.
There are a range of

Intelligence Databases - Your Digital Fingerprint

Think about it - every time you get arrested, apply for a driving licence, or even get cautioned, that information goes somewhere. Intelligence databases are massive digital filing cabinets that store billions of records about criminal activity, suspects, and even regular citizens.

The Police National Database holds over 3.5 billion records from 220 different databases - that's like having detailed files on half the world's population! Meanwhile, the Police National Computer (PNC) tracks 12 million people's arrests and convictions, plus everyone who's ever had a driving licence.

These systems are brilliant for connecting crimes across different areas and catching repeat offenders through DNA matches. However, they're not without problems - the Gangs Matrix was criticised for unfairly targeting young black men, and data leaks have put people's lives at risk.

Key Point: Intelligence databases can solve crimes quickly, but they raise serious questions about privacy and discrimination.

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DNA Evidence - The Game Changer

DNA profiling revolutionised crime solving when scientist Alec Jeffreys developed it in 1985. Since everyone's DNA is unique (except identical twins), it's become the most powerful tool for identifying criminals since fingerprinting was invented.

The first DNA case solved two murders in Leicestershire by testing blood samples from 4,583 local men. Interestingly, Colin Pitchfork was only caught because a colleague reported that he'd paid someone else to take the test for him - showing that even brilliant forensic evidence sometimes needs old-fashioned detective work.

DNA analysis can now work with tiny samples and even use relatives' DNA to catch offenders years later. However, contamination remains a serious risk - just ask Adam Scott, who spent five months in prison due to a contaminated sample.

Key Point: DNA evidence is incredibly powerful but must be handled perfectly to avoid wrongful convictions.

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Surveillance Techniques - Watching and Waiting

CCTV monitoring gives police 24-hour coverage and visual records of crimes, making it invaluable for identification. During major incidents like the 2011 riots, footage released to the media helps the public identify suspects.

Covert surveillance is more targeted - think tracking devices, phone tapping, and undercover officers. Covert Human Intelligence Sources (CHIS) might be undercover police or criminal informants who gather information from the inside.

However, surveillance raises serious ethical concerns. The Colin Stagg case showed how covert operations can go wrong - an undercover female officer tried to trick him into confessing to Rachel Nickell's murder, leading to his wrongful prosecution and £706,000 compensation.

Key Point: Surveillance can be highly effective but must balance crime-fighting with protecting citizens' rights to privacy.

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Eye-Witness Testimony - The Unreliable Truth

Juries love eye-witness testimony and often treat it as the most reliable evidence. The 1976 Devlin Committee found that 74% of cases with only line-up identification evidence resulted in convictions.

But here's the shocking reality - the US Innocence Project found that over 70% of wrongful convictions involved eye-witness misidentification. Our memories aren't video recordings; they're affected by factors like lighting, violence, and weapon focus, where witnesses concentrate on the weapon rather than the offender's face.

Memory retrieval can be distorted by leading questions. Loftus and Palmer's research showed that asking about cars that "smashed" rather than "hit" led witnesses to estimate higher speeds and even "remember" broken glass that wasn't there.

Key Point: Eye-witness testimony feels reliable but is surprisingly unreliable due to how our memory works under stress.

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The Cognitive Interview - Getting It Right

With memory being so unreliable, police need better interview techniques. Cognitive interviews use psychological strategies to improve recall, like asking witnesses to imagine themselves back at the crime scene and report everything they remember, no matter how trivial it seems.

Expert witnesses play a crucial role too. Forensic specialists can analyse blood patterns, explosions, and gunshot residue, while pathologists determine cause of death. Entomologists even use insect development on corpses to calculate time of death - nature's own stopwatch!

Psychologists create offender profiles based on crime scene behaviour, whilst forensic anthropologists identify victims from human remains. However, experts can get it wrong - the Sally Clark case shows how incorrect expert testimony can lead to tragic miscarriages of justice.

Key Point: Proper interview techniques and expert analysis are essential, but even experts make mistakes that can destroy innocent lives.

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Offender Profiling - Reading Criminal Minds

Offender profiling works on the idea that criminals leave behavioural clues just like they leave fingerprints. By analysing how a crime was committed, profilers try to predict the offender's characteristics, lifestyle, and personality.

Typological profiling divides criminals into organised and disorganised types. Organised offenders plan their crimes, control victims, and remove evidence - they're often intelligent but manipulative. Disorganised offenders act spontaneously, leave evidence behind, and often live alone near the crime scene.

The FBI developed this system in the 1970s based on interviews with just 36 serial killers - a tiny sample that may not represent typical criminals. Critics like David Canter argue that profiles are too subjective and speculative to be genuinely helpful.

Key Point: Profiling can help focus investigations, but it's based on limited data and profilers' subjective opinions.

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Clinical and Geographical Profiling

Clinical profiling treats every case as unique. Profilers like Paul Britton use psychiatric knowledge to get inside the offender's mind. However, this approach led to the disastrous Rachel Nickell case, where Colin Stagg was wrongly targeted while the real killer, Robert Napper, murdered again.

Geographical profiling analyses where crimes occur to predict where offenders live. It's based on two principles: criminals choose nearby targets (least effort principle) but avoid areas too close to home (buffer zone principle).

Marauders operate from a home base, moving out in different directions each time. Commuters travel away from home to offend elsewhere. Canter's circle theory suggests drawing a circle through the furthest crimes to find the offender's likely home location.

Key Point: Different profiling methods have varying success rates, but all depend heavily on accurate, complete data.

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Investigative Psychology - The Science of Criminal Behaviour

Investigative psychology, developed by David Canter, combines geographical profiling with deeper behavioural analysis. The offender consistency principle suggests that criminals behave similarly in their crimes and everyday lives - so a degrading rapist likely has problems with women generally.

Criminal narrative themes explore how offenders see themselves: as an "elated hero" seeking adventure, a "depressed victim" with no choice, a "calm professional" doing a job, or a "distressed revenger" getting payback.

This approach has successfully solved various crimes by combining large-scale data analysis with psychological insights. Unlike purely intuitive methods, it uses testable concepts that can be scientifically verified.

Key Point: Investigative psychology offers a more scientific approach to profiling, but still depends on high-quality, accurate data to make reliable predictions.

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Criminology3,376 views·Updated Jun 18, 2026·11 pages

Criminology Unit 3 AC 1.2: Comprehensive Review

Kashan Malik@kashanmalik

Add to Google sources

Ever wondered how police catch criminals using everything from DNA to undercover operations? Criminal investigations rely on a fascinating mix of high-tech databases, forensic science, and psychological profiling techniques that can make or break a case.

of 10

Intelligence Databases - Your Digital Fingerprint

Key Point: Intelligence databases can solve crimes quickly, but they raise serious questions about privacy and discrimination.

of 10

DNA Evidence - The Game Changer

Key Point: DNA evidence is incredibly powerful but must be handled perfectly to avoid wrongful convictions.

of 10

Surveillance Techniques - Watching and Waiting

Key Point: Surveillance can be highly effective but must balance crime-fighting with protecting citizens' rights to privacy.

of 10

Eye-Witness Testimony - The Unreliable Truth

Key Point: Eye-witness testimony feels reliable but is surprisingly unreliable due to how our memory works under stress.

of 10

The Cognitive Interview - Getting It Right

Key Point: Proper interview techniques and expert analysis are essential, but even experts make mistakes that can destroy innocent lives.

of 10

Offender Profiling - Reading Criminal Minds

Key Point: Profiling can help focus investigations, but it's based on limited data and profilers' subjective opinions.

of 10

Clinical and Geographical Profiling

Key Point: Different profiling methods have varying success rates, but all depend heavily on accurate, complete data.

of 10

Investigative Psychology - The Science of Criminal Behaviour

Key Point: Investigative psychology offers a more scientific approach to profiling, but still depends on high-quality, accurate data to make reliable predictions.

of 10