Documents and Chromatography - Forensic Science - Lecture Slides, Slides of Forensics

Download Documents and Chromatography - Forensic Science - Lecture Slides and more Slides Forensics in PDF only on Docsity!

Unit 7: Questioned Documents and Chromatography

 Involves the examination of handwriting, ink, paper, etc. to ascertain the source or authenticity or detect any changes.  Examples include letters, checks, licenses, contracts, wills, passports, suicide notes, receipts, etc.

 Topics

 Handwriting analysis  Ink (and pens)  Paper (and pencils)  Forgery  Codes and Ciphers

 Led to the conviction (and execution) of Bruno Hauptmann in 1930 based on ransom note handwriting.

 Has not always been accepted by the courts.

 In 1999, the US Court of Appeals determined that handwriting analysis qualifies as “expert testimony” and is admissible provided it follows scientific guidelines.

 Line quality—do the letter flow or are they deliberate

 Spacing of words or letters—what is the average space

 Lifting pen—does the author lift his pen between words

 Connecting strokes—how are capital letters connected to lowercase letters

 Pen pressure—how much pressure is applied on the up and down stroke

 Slant—do the letters slant left or right or variable

 Are letters cursive, printed, or both

 Fancy writing habits—unusual loops or curls; unique styles

 Goal is to detect forgeries (documents made, adapted, or falsified in an attempt to deceive someone)  “ACE”

 Analysis of the “knowns” with a determination of the characteristics found in the known.  Exemplars (letters, diaries, cards, personal notes)

 Analysis of the questioned or unknown writing and determination of its characteristics

 Comparison of the questioned writing with the known writing.

 Evaluation of the evidence, including the similarities and dissimilarities between the “questioned” and “known” writing.

 The subject should not be shown the questioned document.  The subject is not told how to spell words or use punctuation.  The subject should use materials similar to those of the document.  The dictated text should match some parts of the document.  The subject should be asked to sign the text.  Always have a witness.  Repeat with the non-writing hand.  Samples should be both requested and collected.