When crimes happen, police use various investigative techniques to catch... Show more
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1,844
โข
Updated Mar 29, 2026
โข
seb ๐ค
@sebaby
When crimes happen, police use various investigative techniques to catch... Show more

Interviews are crucial for gathering information, but they're not always reliable. Police interview two main types of people: eyewitnesses (who saw the crime happen) and expert witnesses (specialists who provide technical advice). However, eyewitness testimony can be seriously flawed - one case shows how a rape victim wrongly identified Ronald Cotton from a photo lineup, leading to his wrongful imprisonment until DNA evidence later freed him.
Forensic techniques involve collecting physical evidence like blood, hair, fingerprints, and DNA from crime scenes. DNA analysis is particularly powerful because everyone has a unique DNA profile, making it brilliant for both proving guilt and innocence. It's highly reliable and can even identify victims when other methods fail.
However, DNA analysis isn't perfect. Suspects must already be on the National DNA Database to get a match, it's expensive, and cross-contamination can happen. Sometimes tiny amounts of DNA can falsely implicate innocent people - like taxi driver David Butler, whose skin condition caused his DNA to appear under a murder victim's fingernails when he was just giving her change.
Key Point: DNA evidence helped solve many cold cases and free wrongly convicted people, but it's not foolproof and requires careful handling to avoid contamination.
Surveillance techniques include CCTV cameras that constantly record public spaces and can deter crime. Covert surveillance involves secretly monitoring specific suspects through phone tapping and hidden cameras. This works brilliantly for serious crimes like terrorism because suspects don't know they're being watched, so they act naturally.
The downsides? CCTV cameras can't move to follow suspects, image quality often suffers, and footage gets deleted after 30-90 days. Covert surveillance raises privacy concerns and can lead to human error, plus there's the risk of entrapment where police essentially trick someone into committing a crime.
Offender profiling creates a psychological picture of criminals based on their behaviour and crime patterns. Geographical profiling analyses where crimes happen to predict where the offender lives. Typological profiling categorises crimes as either organised (planned, intelligent) or disorganised (impulsive, chaotic).
Profiling helped catch George Metesky, the "Mad Bomber" of New York in the 1940s, when he matched the profile almost perfectly. But it's not always accurate - criminals don't always fit neat categories, and profiles can be so vague they could apply to loads of people (called the Barnum effect).
Intelligence databases store vast amounts of information that police forces can quickly search and share. The Police National Database holds criminal activity records, while the Police National Computer includes DNA databases. International databases like INTERPOL help UK police access worldwide information on organised crime and exploitation.
These databases speed up investigations massively, but they're not without problems. Young people and ethnic minorities are over-represented, hackers could potentially breach security, and human error can corrupt the data.
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help โ all at your fingertips.
App Store
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because itโs too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didnโt even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as Iโm sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH ๐๐๐ฒ๐ค๐โจ๐๐ฎ
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because itโs too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didnโt even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as Iโm sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH ๐๐๐ฒ๐ค๐โจ๐๐ฎ
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
seb ๐ค
@sebaby
When crimes happen, police use various investigative techniques to catch the culprits and build strong cases for court. From interviewing witnesses to analysing DNA evidence, each method has its own strengths and weaknesses that can make or break a criminal... Show more

Access to all documents
Improve your grades
Join milions of students
Interviews are crucial for gathering information, but they're not always reliable. Police interview two main types of people: eyewitnesses (who saw the crime happen) and expert witnesses (specialists who provide technical advice). However, eyewitness testimony can be seriously flawed - one case shows how a rape victim wrongly identified Ronald Cotton from a photo lineup, leading to his wrongful imprisonment until DNA evidence later freed him.
Forensic techniques involve collecting physical evidence like blood, hair, fingerprints, and DNA from crime scenes. DNA analysis is particularly powerful because everyone has a unique DNA profile, making it brilliant for both proving guilt and innocence. It's highly reliable and can even identify victims when other methods fail.
However, DNA analysis isn't perfect. Suspects must already be on the National DNA Database to get a match, it's expensive, and cross-contamination can happen. Sometimes tiny amounts of DNA can falsely implicate innocent people - like taxi driver David Butler, whose skin condition caused his DNA to appear under a murder victim's fingernails when he was just giving her change.
Key Point: DNA evidence helped solve many cold cases and free wrongly convicted people, but it's not foolproof and requires careful handling to avoid contamination.
Surveillance techniques include CCTV cameras that constantly record public spaces and can deter crime. Covert surveillance involves secretly monitoring specific suspects through phone tapping and hidden cameras. This works brilliantly for serious crimes like terrorism because suspects don't know they're being watched, so they act naturally.
The downsides? CCTV cameras can't move to follow suspects, image quality often suffers, and footage gets deleted after 30-90 days. Covert surveillance raises privacy concerns and can lead to human error, plus there's the risk of entrapment where police essentially trick someone into committing a crime.
Offender profiling creates a psychological picture of criminals based on their behaviour and crime patterns. Geographical profiling analyses where crimes happen to predict where the offender lives. Typological profiling categorises crimes as either organised (planned, intelligent) or disorganised (impulsive, chaotic).
Profiling helped catch George Metesky, the "Mad Bomber" of New York in the 1940s, when he matched the profile almost perfectly. But it's not always accurate - criminals don't always fit neat categories, and profiles can be so vague they could apply to loads of people (called the Barnum effect).
Intelligence databases store vast amounts of information that police forces can quickly search and share. The Police National Database holds criminal activity records, while the Police National Computer includes DNA databases. International databases like INTERPOL help UK police access worldwide information on organised crime and exploitation.
These databases speed up investigations massively, but they're not without problems. Young people and ethnic minorities are over-represented, hackers could potentially breach security, and human error can corrupt the data.
Our AI Companion is a student-focused AI tool that offers more than just answers. Built on millions of Knowunity resources, it provides relevant information, personalised study plans, quizzes, and content directly in the chat, adapting to your individual learning journey.
You can download the app from Google Play Store and Apple App Store.
That's right! Enjoy free access to study content, connect with fellow students, and get instant help โ all at your fingertips.
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Smart Tools NEW
Transform this note into: โ 50+ Practice Questions โ Interactive Flashcards โ Full Mock Exam โ Essay Outlines
App Store
Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because itโs too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didnโt even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as Iโm sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH ๐๐๐ฒ๐ค๐โจ๐๐ฎ
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan S
iOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha Klich
Android user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
Anna
iOS user
Best app on earth! no words because itโs too good
Thomas R
iOS user
Just amazing. Let's me revise 10x better, this app is a quick 10/10. I highly recommend it to anyone. I can watch and search for notes. I can save them in the subject folder. I can revise it any time when I come back. If you haven't tried this app, you're really missing out.
Basil
Android user
This app has made me feel so much more confident in my exam prep, not only through boosting my own self confidence through the features that allow you to connect with others and feel less alone, but also through the way the app itself is centred around making you feel better. It is easy to navigate, fun to use, and helpful to anyone struggling in absolutely any way.
David K
iOS user
The app's just great! All I have to do is enter the topic in the search bar and I get the response real fast. I don't have to watch 10 YouTube videos to understand something, so I'm saving my time. Highly recommended!
Sudenaz Ocak
Android user
In school I was really bad at maths but thanks to the app, I am doing better now. I am so grateful that you made the app.
Greenlight Bonnie
Android user
very reliable app to help and grow your ideas of Maths, English and other related topics in your works. please use this app if your struggling in areas, this app is key for that. wish I'd of done a review before. and it's also free so don't worry about that.
Rohan U
Android user
I know a lot of apps use fake accounts to boost their reviews but this app deserves it all. Originally I was getting 4 in my English exams and this time I got a grade 7. I didnโt even know about this app three days until the exam and it has helped A LOT. Please actually trust me and use it as Iโm sure you too will see developments.
Xander S
iOS user
THE QUIZES AND FLASHCARDS ARE SO USEFUL AND I LOVE Knowunity AI. IT ALSO IS LITREALLY LIKE CHATGPT BUT SMARTER!! HELPED ME WITH MY MASCARA PROBLEMS TOO!! AS WELL AS MY REAL SUBJECTS ! DUHHH ๐๐๐ฒ๐ค๐โจ๐๐ฎ
Elisha
iOS user
This apps acc the goat. I find revision so boring but this app makes it so easy to organize it all and then you can ask the freeeee ai to test yourself so good and you can easily upload your own stuff. highly recommend as someone taking mocks now
Paul T
iOS user