Unit IV Guided Notes: Document Analysis & BallisticsName:__________________________

What sort of cases involve questioned documents?

A questioned document is ____________________________________________________________________________ ___________________________________________________________________.

These investigations include:

· Trying to determine the source of a threat or note

· Identifying forgeries and counterfeits

· Identifying alterations made to documents

Paper Comparison

Investigators may try to compare the paper of a questioned document with that of an ____________________ (sample from known source).

Investigators will compare:

___________________________ occurs when the electrons of a material absorb short-wave energy (i.e. UV light) and immediately emit longer wave energy (i.e. visible light). Occurs because the electrons become excited then almost immediately return to lower energy orbitals.

· Material paper is made from

· Density

· Thickness

· Dyes / bleaches

_______________________________ are near-transparent designs added to papers, often for the purpose of making the paper harder to forge. The mark can be seen by holding the paper up to the light. The design is made by _____________________________________ in certain areas.

· Fluorescence under UV light

· Watermark

Ink Comparison

Investigators may try to compare the ink of a _____________________________________ with that of an ___________________________(sample from known source).

Alternatively, ink may be analyzed to show that a document has been altered or back-dated.

How might ink analysis show that a document has been altered?

How might ink analysis show that a document has been back-dated?

The main technique used to identify / compare inks is ____________________________________________________.

First, however, the ink has to be ________________________ from the questioned document.

1. Samples of the questioned ink are collected by punching out ‘_____________________’ with a hypodermic needle

2. The microdots are put in a small vial with _________________________to separate the ink from the paper. The ink/solvent mix can then be analyzed using thin layer chromatography.

Thin layer chromatography is a method used to separate components of a mixture.

· In thin layer chromatography, a sample is placed near the bottom of a plate (the _____________________________). Usually, the plate is made of ____________________________________ ________________________________________________________________________________________.

· The plate is placed within a small chamber containing a small amount of liquid solvent (the _______________________). The sample should be just above the solvent.

· The solvent (mobile phase) moves up the plate (stationary phase) by ___________________________________.

· ____________________________________________________________________________________________ ____________________________________________________ depending on their relative affinity for the solvent vs the plate. (i.e. the more they are attracted to the solvent the faster/farther the molecule will climb up the plate.)

· The _________________________________________of each component in the mixture can be calculated and compared to an exemplar or to a database maintained by the Secret Service & IRS

Calculating Rf Values

Counterfeiting and Money Security

US money has a number of features designed to make counterfeiting more difficult. These include:

· Use of subtle colors that are difficult to duplicate

Did you know?

The US Secret Service was founded in 1865 to combat counterfeiting. Historians estimate that up to 1/3 of all money in circulation at that time was counterfeit.

Even today, the USSS confiscates about $80 million in phony money each year.

· Large, vivid portrait that stands out from background

· Portrait watermark bills greater than $4

· Two ‘5’ watermarks on $5 bills

· Color changing ink (green – copper) on number for all bills

· Color changing ink (green – copper) on bell for $100

· 3D security ribbons

· Raised printing

Alterations, Erasures, and Obliterations

Investigators may also need to examine whether a document has altered from the original.

An ______________________________________________________________________________________.

· Can be detected with a microscope

· Sometimes the original ink my still be detected using UV or infrared light

An ___________________________________________ is when writing has been purposefully made unreadable by

_____________________________________________________________.

· If both inks used are the same, its nearly impossible to tell what the first markings were.

· If different inks were used, infrared photography may reveal the first ink

Handwriting Analysis

When people are writing naturally (without attempt to disguise their writing or copy someone else’s), handwriting is thought to be unique.

Handwriting can vary in:

· Letter shape / overall style

· Line quality (shaky, smooth, wavering, rhythmic, etc)

· Spacing of words and letters

· Size of letters

· Pen lifts

· Connecting strokes

· Beginning & ending strokes

· Pen pressure & differences between up and down pen pressure

· Slant

· Baseline (straight, move upward or downward, above or below line0

· Placement of _______________________ (crossing of t’s and dotting of I’s and j’s)

Deliberately disguised handwriting is more difficult to correctly identify, but most people find it difficult to disguise handwriting for long periods of time.

In order to obtain good writing exemplars detectives will do the following:

· Use samples that are longer than a page

· Dictate the writing at least 3 times (disguised writing will show more natural variation than normal writing

· Use the same phrases and words that are in the questioned document

· Instruct that the person not only write in capitals or only in lower case

· Combine signatures with regular writing

Ballistic Analysis Guided NotesName:_______________________

Types of Firearms

________________________ are designed to be held and fired with one hand.

· ___________________________ can only fire one shot before being manually reloaded.

· A ____________________________ contains several cartridges in a revolving cylinder. When one shot is fired, the cylinder rotates so that the next cartridge is in place to be fired. _______________________________________________.

· A _______________________________________________ contains a magazine with several cartridges; as one bullet is fired the next cartridge is loaded.

· An ___________________________________ (e.g. machine gun) will continue to fire bullets as long as the trigger is held down (________________________________________________________).

Did you know?

A _____________ is what is fired (the projectile that exits the barrel of the firearm). A ______________ contains the bullet plus a casing, primer, and propellant.

_____________________________ are fired while resting on the shoulder.

· _________________________ have cartridges and bullets similar to handguns.

· ____________________________ ammunition is called a __________________ and contains numerous ball-shaped projectiles called ____________.

Like handguns, rifles and shot guns may be single shot, semi-automatic, or automatic.

Bullet Comparisons

When a bullet is fired from a gun, the inner surface of the gun barrel leaves markings along the bullet that allow investigators to:

· match a bullet to a particular type of gun (by examining class characteristics against a database)

-or-

· match a bullet to a specific gun (by comparing individualized characteristics of the evidence bullet and a test bullet fired from a confiscated gun).

Why do guns leave marks on bullets?

· The interior (______________) of gun barrels are _____________________(impressed with spiral _________________________) in order to make the bullet spin as it is fired – this ensures that the bullet does not tumble end over end but instead follows a smooth and accurate course.

· The spaces between the grooves within the bore are called _____________________.

· The bore diameter (from land to land) is the ___________________ of the gun.

Class characteristics

The lands and groves of the gun bore leave a negative impression on the bullet (called _____________________________) that can help identify the type of gun a bullet was fired from.

Specifically, investigators will examine

· ______________________________________________________________________

· ______________________________________________________________________

Class characteristics of known weapons are maintained in an FBI record called the General Rifling Characteristics File.

Individualized characteristics

Imperfections in the gun bore produce very fine lines, or ____________________________, on bullets. These striations will are unique to the gun.

To determine that two bullets were fired from the same gun,

investigators examine both bullets with a comparison microscope

to show that the striations match exactly.

NIBIN – National Integrated Ballistics Information Network

A program maintained by FBI and ATF to store and match images from bullets and cartridges retrieved from crime scenes and test fires of recovered weapons.

· More than 800,000 images stored

· Has matched more than 28,000 bullets or cartridges

· As with AFIS, any possible matches found must be verified by an experienced forensic expert.

Gunpowder and Primer Residue

When a person fires a gun, gun powder and primer residue typically blow back onto the shooter.

Gunpowder contains _____________________ – but so do many other things including tobacco, some cosmetics, fertilizers, etc.

Now, investigators focus on looking for _____________________ and __________________ which are found in most gun primers (and are less common elsewhere, though still present in brake linings and fireworks).

Gunshot residue can be collected from suspects through __________________________ or through ________________________ each hand with cotton soaked in 5% nitric acid.

· Adhesive tape samples are first examined under a _____________________________ _______________________________ – gunshot residue has a characteristic size and shape. If the SEM microscope is also attached to an ________________________ analyzer then the elemental composition of the particles can also be determined.

· Swabbing samples can be chemically analyzed but cannot be viewed under the microscope.

Modern methods have greatly reduced the ______________________________ of gunshot residue analysis.

However, gunshot residue analysis still has a ________________________________________.

· Gun powder residue is easy to remove by washing hands and it will typically wipe off within 2-6 hours after firing a gun.

· Primers for 0.22 caliber guns often do not contain barium or antimony and so cannot be detected using traditional methods.

What is a false positive? A false negative?