CRIME DETECTION MODELLING BY USING NUMERICAL METHODS
1 CRIME:
In most countries the detection of crime is the responsibility of the police though special law enforcement agencies may be responsible for the discovery of the particular type of crime.
Example: Customs departments may be charged with computing smuggling and related offenses.
Crime detection falls in to three distinguishable phases the discovery that a crime has been committed the identification of a suspect and the collection of sufficient evidence to indict the suspect before a court.
Example: Electronic eavesdropping surveillance interception of communication and infiltration of gangs.
Fig: 1 FLOWCHAT OF CRIME DEFELATION
1.3. STEPS OF CRIMINAL CASE:
The 5 basic steps of a criminal proceeding are
·
Arrest
·
Preliminary hearing
·
Grand jury investigation
·
Arraignment in criminal court
·
Trial by jury
1.4. CAUSES OF CRIME:
·
Poverty this is perhaps one of the most concrete
reasons why people
·
commit crime
·
Peer pressure new form
of concern in the modern world
·
Drugs always been highly criticized by critics
·
Politics
·
Religion ,family conditions, the society ,unemployment.
1.5. THE CRIME SCENE SKETCH:
·
Measure and outline
area
·
North should be at the top
of the paper
·
Determine the scale
·
Take the longest
measurement at the scene and divide it by the longest measurement of the paper used for the Sketching.
Ø 1/2″ = 1 small rooms.
Ø
1/8″ = 1 very large rooms.
Ø
1/8″ = 10 large land area.
2. CRIME PREVENTION AND TECHNIQUES
2.1. INVOLVES:
Recognition.
↓
Identification
↓
Individualization
↓
Reconstruction
2.1.1 RECOGNITION:
• Scene survey documentation collection
2.1.2 IDENTIFICATION:
• Classification of evidence
2.1.3 INDIVIDUATION:
• Comparison testing
evaluation and interpretation
2.1.4 RECONSTRUCTION:
• Sequencing events
reporting and presenting
2.2. THE CRIME SCENE SKETCH:
•
Measure and outline
area
•
It doesn’t stretch
•
Use conventional units of measurements
•
Inches
•
Feet
•
Centimeters
•
Meters
2.3. CRIME SCENE RECONSTRUCTION:
•
Data collection
•
Conjecture
•
Hypothesis formulation
•
Testing
•
Theory
3.FLOWCHART AND CRIME NOTES
The location of possible targets homes people as well as general environmental goes like levels of disorder housing density and surveillance researches also include knowledge offenders might have about target vulnerability for instance tricks learned from burglarizing nearby and what they found was two kinds of crime hotspots.
Supercritical which formed from a rapid chain reaction of law less ness and subcritical a large spike in a crime in an otherwise stable area in a supercritical situation small spikes in crime grow and spread when increased police force is applied new hotspots.
But off existing once they reform around small spikes in a crime to continue away from areas of police presence the crime is displaced police suppression is a cat and mouse game something very different happens when police are added to a sub critical hots
The surrounding are relatively stable so one suppression is applied the hotpots is reduced or eradicated completely and even when suppression efforts are removed the hotpots doesn’t really. Since strategy won’t work for both kinds of hotpots.
This key difference may help law enforcement tailor their crime strategies to different neighborliness ultimately thought hotpots maybe similar sizes and distribution
The research shows that looking at the dynamic of crime is important in gauging the best police response and that could be a fundamental step towards better prediction and crime prevention strategies and an even safer future for cities.
4. NOTES OF CRIME:
Imagine someone is committing crime throughout local area on a regular basis may be they have committed 5 crimes in the last month at these locations how could we go about catching this person.
One thing we can do is try finding a patterns in crime location in order to make a prediction about the next one that can be tricky through since there likely a huge elements of randomness but decades ago Kim Ross mo. a PhD criminologist had another idea he tried to find a formula instead could find.
Where the criminal likely lives based on the past data he knows that criminals often don’t commit crimes right by their own home but also they don’t go too far away so from the data you can determine a quote hot zone fig★
Fig ★ HOT ZONE
Which is not too close or too far from the crime scene it has a high probability of the person living there this is his equation for determining those probabilities. I know it looks complex but its actually not as bad as you think like take this Pi, j parts.
To see the crime scene in map and put a gird over it any given squares will be in some row we will label i and column will label j, Pi, j is probability that the criminal lives in the square. How you calculate that value for any square is with this right side of the equation.
Formula for crime detection:
(| Xi-xn|+|Yj -yn|)f → 1 𝑠𝑡 𝑡𝑒𝑟m
(2𝐵| Xi-xn|+|Yj -yn|) g
→ 2 𝑛𝑑 𝑡𝑒𝑟𝑚
Now take this denominator equation, (|Xi-xn |+|Yj -yn|) f this 1stpart just means take the arbitrary grid you are analysing and one of the crime scene and subtract these x corps donets which gives you this distance.
The absolute value just ensure that its positive then |Yj -yn| parts just says do the same thing with the y axis which gives us this length add those up and we get the distance between the gird and the crime scene no it’s not the straight – line distance.
If you cannot move to agonal and as we saw this term is in the denominator which means as that distance goes up the entire fraction and thus the probability go down this is expected because like .I said these criminals usually don’t go super far to commit a crime so a larger distance between our square and the crime scene means a smaller Probability the criminal lies.
There at least for this laughter but remember criminals don’t commit these crime close to this homes either and that where this side of the equation comes.
You have that same distance down here subtracted from something known as a buffer zone which is just a 2B constant determined by what works best with known data or past crime so as
distance goes up the entire denominator actually decreasing making the whole fraction.
Probability go up so physically if you are too close to the crime scene probability is low that the criminal lives there but as you get further the probability increase that is of course until you pass a certain point which is where the left side of the formula comes in again after the distance and these 2 fractions change in opposite ways which is essentially.
The balancing act that creeps the hot zone of high probability that isn’t too close and isn’t too far from the crime scene for is sort of a constant that I am not going to go in to ∅ i j and that g, f and B are constant. That just make certain parts of this equation matter more than other or they add more weights to certain parts then lastly this part.
We calculated these 2 fractions for every single crime committed and add the results do this for square on our gird and we create a heat map of probability. Actually is the equation output based on real crimes of a serial killer from the 70s named Richard chase you can see the crime locations in green and the formula predicts his residence to be somewhere in this dark region his actual residence is plotted here in purple exactly as expected so that least in the case Rasco’s formula works.
5. CRIME SCENE CONTROL
The actions which the first arriving officer at the crime scene takes to make sure that the integrity of the scene maintained. Control also includes preventing people at the scene from becoming combatants and separating witnesses.
5.1 DRAWBACKS:
·
No bobby on the beat
·
Local police officer
in the local community
·
Large amount of data but is there a significant impact on detecting and reducing crime
overal
5.2 BENEFITS:
·
Administrative duties completed
more quickly
·
Tools available to help track down criminals
·
Communication improved
·
Evidence collection tracking
analysis and availability improved
·
Amount of data available.
5.3 SCALING THE INVESTIGATION TO THE EVENT:
·
The crime scene must be secured preserved and recorded until evidence is collected
·
Existing contamination must be
considered and recorded
·
Cross contamination must be prevented
·
Exhibits must be identified preserved
collected and secured
to pressure the chain of continuity
5.4 CRIME SCENE ANALYSIS PROCESS:
·
Crime analysts study
crime reports arrests
reports and police cells for service calls for service
to identify emerging
patterns series and trends
as quickly as possible.
·
The analyse these phenomena for all relevant factors
sometimes predict or forecast future occurrence and issue bulletins reports and alert to their
agencies.
5.5 CRIME SCENE CONTROL:
·
The actions
which the first arriving officer
at the crime scene takes to make sure that the integrity of the scene is maintained.
·
Control also includes
preventing people at the scene from becoming
combatants and separating witnesses.
5.6.1 CRIME SCENE MAPPING:
·
Triangulation- uses to two points
at the crime scene to map each piece of evidence
·
Coordinate or grid – divides the crime scene into squares
for mapping
·
Suspended polar coordinate-for use in mapping evidence in a hole
·
Baseline- set a north or south line and measure each piece of evidence
from this line.
5.6.2 MICROSCOPIC CRIME SCENE:
·
Based on the size
·
Trace evidence
·
Gunshot residue
·
Tire treads
·
Hair samples
·
Mites found in clothes
5.6.3 CRIME SCENE DOCUMENTATION:
·
Take notes at the crime scene
·
Videotape the crime scene
·
Photograph the crime
scene
No comments:
Post a Comment