Questioned Document Examination

Part II

Other Responsibilities

• The Document Examination Unit not only examines questioned documents, but works with other areas that link to forgery and fraud.

• One such area is Cryptology or Cryptography.

• Cryptography comes from the Greek words kryptos (secret) and graphos (writing). 

• Codes and ciphers are examples of cryptography.

Codes

• Codes use symbols or groups of letters to represent words or phrases.

• Codes may be as easy as the non-secret SOS distress code or so secretive that both sender and receiver need a Code Book.

Morse Code

• In 1838, Samuel Morse invented Morse Code.

• Morse Code is not really a code, but an electro-magnetic telegraph system that uses a system of dots and dashes.

• However, codes were sent in Morse Code format and then decoded.

• Morse Code was a very important message system during World War I.

Morse Code

Listen to a Morse Code Message. What does it say?

The Enigma

• During World War II, the Germans used the Enigma machine.

• This machine could put a message into code in over 150 MILLION MILLION MILLION different ways.

• The Germans believed that the Enigma was invincible, but eventually the code was broken by the Allies.

Colossus• Colossus was the machine that helped to

break the Enigma code.• Colossus was the world’s first programmable

computer.

Ciphers

• In a cipher one letter is replaced with another by either a simple or a complex scheme

Ciphers

• Knowing English Letter Frequency helps to break a cipher. E is the most commonly used letter.

Invisible Ink

• Codes or secret messages may be written with invisible ink.

• The author uses ordinary paper, but the writing will disappear when the ink dries.

Retrieving the Message

• Seeing the invisible message depends on the type of ink used.

• UV light, heat, chemical developers or a combination of these will reveal the hidden message.

Espionage

• On September 22nd, 1776 Nathan Hale was the first American captured and executed for spying

• As President, Washington established a fund for secret or covert missions

Civil War

• Many of the most successful spies were women

• Cushman received an honorary major’s commission from Lincoln

WWI

• 1917 Federal espionage law was passed

• Intelligence in WWI focused on code breaking and intercepting communications

Pearl Harbor

• The bombing of Pearl Harbor blamed on major intelligence failure

• Led to OSS/CIA

OSS

• Office of Strategic Services was America’s first intelligence agency

• By 1945, agents scattered throughout the world

• Donovan, head of OSS, had plans to expand agency that were leaked to newspaper

• Country panicked, Roosevelt died and Truman eliminated the OSS in 1945

CIA

• Central Intelligence Agency created as part of the National Security Act of 1947

• Confidential and covert so successes rarely known and publicized

• Failures were exposed

• Korean War

Mission

• To serve as “the eyes and ears of the nation and at times its hidden hand”

• Number of employees is classified

• Budget is not released• Considered on of the top

50 employers for new college graduates

Polygraph Testimony

• In many fraud investigations, the suspect is asked to take a polygraph or “lie detector” test.

• These tests are very controversial and the results are not considered reliable.

How does a Polygraph Work?

• Lying is a defend mechanism to avoid trouble.

• It is not always obvious that someone is lying.

• A polygraph is an instrument that measures physiological reactions.

The Measurements

• 4 to 6 sensors are attached to the body.

• Multiple signals are gathered from each sensor and recorded.

• These recordings are the measurements of heart rate, blood pressure, respiratory rate and electro-dermal activity.

The Questions

• The participant is asked 3 to 4 simple questions to establish “norms”.

• These questions would give baseline readings for the “truth”.

• Then the participant will be asked other questions that involve the incident as well as control questions.

The Results

• Results are subjective and may be misinterpreted as:

• False positive- truthful person decided to be deceptive.

• False negative- deceptive person decided to be truthful.

• False positives occur more.

“Beating” a Polygraph

• Ways that people try to trick the device include:

• Taking sedatives• Applying antiperspirant

to their fingertips• Placing tacks in their

shoes• Biting their tongue, lip

or cheek

The Court

• Many states do not allow any polygraph testimony.

• Other states allow the testimony with stipulations (both parties agree to admit the results as evidence).