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Introduction to Forensic Scienceand the Law

• Fourth amendment protects citizens against “unreasonable search and seizures”

• Police and crime scene investigators need to obtain search warrant from a judge

• Only law enforcement officers may obtain a search warrant; attorneys, private investigators and private citizens cannot obtain a search warrant.

Collecting evidence- Executing a search warrant

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Introduction to Forensic Scienceand the Law

• Steps in securing a valid search warrant1.Prepare an affidavit: Must describe the location to be searched, items to be searched for and reason why officers expects the items are at the location (probable cause)

2. Prepare the warrant: This the official document that the judge must sign to give permission for the search.

Collecting evidence- Executing a search warrant

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Introduction to Forensic Scienceand the Law

• Steps in securing a valid search warrant3. Get the warrant signed: the warrant and affidavit must be presented to judge by an officer. If the judge determines that there is probable cause, he signs the warrant, this makes it official.

http://www.huffingtonpost.com/2013/09/04/othello-russell-police-raid_n_3865655.htmlhttp://miami.cbslocal.com/2013/09/03/police-search-reviewed-after-brownsville-mans-death/

Collecting evidence- Executing a search warrant

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Introduction to Forensic Scienceand the Law

• In order for a warrant to be issued the following requirements must be met:

1.Probable cause: cannot be just a hunch or gut feeling

• Must be suspicion of illegal activity supported by evidence

• Information obtained from a reliable informant

Collecting evidence- Executing a search warrant

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Introduction to Forensic Scienceand the Law

2. Specificity of the search: must state exactly what police are looking for.

3. Area of search: The area to be search must be explicitly stated.

Note: This can be very tricky, because if the warrant states that officers will be searching the house, any garage or shed is off limits.

Collecting evidence- Executing a search warrant

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Introduction to Forensic Scienceand the Law

Protecting the evidence begins with the “SEVEN S’s OF CRIME-SCENE INVESTIGATION”1.Securing the scene is the responsibility of the first-responding police officer (first responder).

• The safety of all individuals in the area is the first priority. Preservation of evidence is the second priority.

Protecting the evidence

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Introduction to Forensic Scienceand the Law

Protecting the evidence begins with the “SEVEN S’s OF CRIME-SCENE INVESTIGATION”• The officer protects the area within which the crime

occurred, restricting all unauthorized persons from entering.

• Transfer, loss, or contamination of evidence can occur if the area is left unsecured

• The first officer has to keep a security log of anyone who visit the crime scene.

Protecting the evidence

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Introduction to Forensic Scienceand the Law

Protecting the evidence begins with the “SEVEN S’s OF CRIME-SCENE INVESTIGATION” 2. Separating the witnesses: This done to prevent

witnesses from working together to create a story (collusion)

3. Scanning the scene: A preliminary survey of the scene needs to be done to see where photos need to be taken or to determine if there is a primary and secondary crime scene

Protecting the evidence

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Introduction to Forensic Scienceand the Law

Protecting the evidence begins with the “SEVEN S’s OF CRIME-SCENE INVESTIGATION” 4.Seeing the Scene: Crime scene examiner needs take a

view of the crime scene from several angles5.Sketching the scene: An accurate rough sketch of the

scene includes-position of the body (if there is one), and any other evidence.

Protecting the evidence

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Introduction to Forensic Scienceand the Law

Protecting the evidence begins with the “SEVEN S’s OF CRIME-SCENE INVESTIGATION” 6. Searching for evidence: Based on location, and number

of investigators, any of the following search method may be used-spiral, grid, linear, or quadrant.

7. Securing and collecting evidence: Evidence must be properly packaged, sealed and labeled and the chain of custody must be maintained.

Protecting the evidence

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Introduction to Forensic Scienceand the Law

• Gathering evidence is not a haphazard process, rather, there is an order to gathering evidence

• The first evidence searched for and collected is the most fragile, most likely to be lost, damaged, or contaminated.

• Each piece of evidence must be packaged separately in order to avoid damage and cross contamination.

We will explore this topic in greater detail

Gathering the evidence

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Introduction to Forensic Scienceand the Law

•Chain of custody: the documented and unbroken transfer of evidence

•The chain of custody requirement is based on the idea that if evidence is left unsupervised after collection, someone can tamper with it and it’s no longer reliable and therefore inadmissible.

Preserving the integrity of the evidence

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Introduction to Forensic Scienceand the Law

•evidence gets a form attached during collection that anyone who takes custody must fill out with information describing what the item is, who collected or handled it, when it was collected, where it  was collected, why was it collected, and an accompanying signature

Preserving the integrity of the evidence

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Introduction to Forensic Scienceand the Law

Preserving the integrity of the evidence