The science behind the forensic analysis is to compare the unknown or questioned with known standards. This is true for both fingerprint and questioned document examinations.
Fingerprint never changes but handwriting or signature does. In fact, no two handwriting/signature samples can be exactly the same.
Both disciplines have different concepts of individuality. So, how to meld them when a QDE has fingerprints on a questioned document?
Should the examiner process fingerprint first? Or questioned document? Which one should be prioritized? What types of development techniques are employed?
Like these questions, this post addresses a number of similar queries related to fingerprint development in questioned document cases.
Which One should be Preferred: Fingerprint or Questioned Documents?
Rule of thumb is: Document examination should be performed prior to the development of fingerprint.
Thus, a Questioned Document Unit (QDU) should process examination procedures— usually nondestructive— and then submit or handle them to the fingerprint development unit.
But this isn’t always the case.
Historically, some federal agencies looked for finger marks before examining QD. The idea was to extract as much information as possible from documents in a short time.
Today, when both disciplines are involved, the experts should work together to develop a working strategy.
In either case, one examiner must maintain the integrity of the evidence so that future analysis can be carried out by another disciplinary examiner.
Why is Questioned Document Analysis Preferred over Fingerprint?
Because fingerprints can be developed even after a document (fingermarks soaked in paper) has been examined by QDU, the opposite cannot always be true.
Prints on paper surfaces are developed using the chemical method (I will later state why the chemical method is used) that are usually destructive. This leads to sabotaging the questioned document examination.
Disadvantages of Using Fingermarks Prior to Questioned Document Analysis
Following are the reason why the majority of forensic organization services prefer questioned document analysis over fingerprints.
- Developing chemicals applied using cotton can alter the fibers on indentation marks.
- May weakens the obliteration.
- Hinders erasure examination.
- Pencil writing may become unreadable if chemically treated.
- Chemical might wipeout or smear the inks from paper.
- Interfere with ink analysis and dating.
- May cause permanent stains.
- Stains may obliterate the writing, signatures, or printed features of questioned documents.
This also raises extra caution to the QD examiner when handling documents, and avoids using destructive techniques for document analysis. Later, the QDs should be submitted for fingerprinting as soon as possible.
How to Handle Questioned Documents With Fingerprints?
A. Handling While Questioned Document Analysis
- Should wear white cotton gloves when handling original sheets that will need further fingerprint development (actually it doesn’t matter, each QDs should be handle with gloves on).
- Handling should be done with edges.
- Return the questioned documents to a protective environment (mylar sheets or envelopes) to minimize any potential damage or addition of marks while not in use.
- No other papers were placed with QDs. Separate mylar sheets should be used for different documents.
- Avoid papered documents to exposure to strong light and heat.
Question: Why are cotton gloves worn by Forensic Document Examiners? (Check FAQ)
B. While Forwarding QDs for Fingerprint Development
- Cotton gloves should be worn to avoid any addition of fingermarks.
- Use protective measures by placing QDs in the sleeves of envelopes without folding.
- Hold from the sides and slightly sleek them into the protective envelope.
- Label the envelope for fingerprinting and maintained chain of custody.
How to Get Fingerprints from Paper Questioned Documents?
Before developing prints, the prior condition of QDs should be registered. For this, a scaled photograph should be taken. This will ensure the integrity of evidence if being questioned later.
Latent Prints: Most common are fingermarks and writer’s palms.
- Chemical processing using ninhydrin, physical developer, and DFO (1,8-Diazafluoren-9-one), or
- Imaging using a laser, alternative light, and appropriate filters, and finally
- Documenting with photography
Visible Prints: Directly photographed
Table: Paper Types and Fingerprint Developing Techniques
|S.No.||Questioned Documents||Fingerprint Development Techniques|
|1.||White Paper||Ninhydrin, Physical developer, Iodine fuming, DFO|
|2.||Tissue paper||Ninhydrin, DFO, Iodine fuming|
|4.||Matte finish paper||DFO, anthracene (fluorescence)|
|5.||Multicolor paper||DFO, anthracene (fluorescence)|
|6.||Glossy paper||Powder (non-magnetic), Cyanoacrylate|
|7.||Polymer banknotes||Cyanoacrylate, powder|
|8.||Water smudge documents||Small Particle Reagent (SPR)|
Documentation of Fingermarks on Questioned Document
Following are some questions that a fingerprint examiner should document in their report when dealing with fingermarks on a forensic examination document.
- What are the temperature and humidity level of the laboratory?
- Where the mark is located on the document?
- What type of surface does the document have on which prints were developed?
- What fingerprint development techniques were used by the examiner?
- What type of prints are developed? (Fingermarks, palm marks)
- How many prints are on documents?
Can DNA Extract from a Fingerprint on Questioned Document?
Yes, there is a possibility of getting DNA from fingermarks on questioned documents. The most common term to describe is “touch DNA.”
The science behind this is that when the finger touches the paper it not only leaves ridges but also cells.
For getting DNA, you have to swab the paper surface with damp cotton buds where fingermarks are most likely to be present.
Moreover, the collection of swabs for DNA must be done before questioned document analysis (if involves ESDA) and fingerprint development technique.
If you handle or write over the paper, your fingerprint may be on it. Furthermore, if you have very dry fingers, or use glossy papers, or gloves-packed fingers, there is a chance they won’t be able to capture your finger ridges.
Chemical methods including ninhydrin, DFO, iodine fuming are some of the best methods for making finger marks visible on a porous surface like paper. However, if the paper is glossy, powder methods can be employed too.
Because, research finds out that with thin rubber gloves, there is a chance that your fingermarks may be captured on paper. This is the same reason why FDEs are instructed to wear white cotton gloves when examining questioned documents.
Forensic documents are instructed to wear thick rubber or white cotton gloves. I personally prefer to have white cotton gloves for document analysis because my hands feel less perspiration. If your hands perspire more, you can try white cotton gloves too.
- Legal Obligation of Person’s Fingerprints Over Questioned Documents
- Is it possible to remove a fingerprint from paper?
- Can Fingerprints be Lifted from Paper?
- 14 Myths of Fingerprints And Questioned Documents: A Forensic Study
- A Guide for Submitting Questioned Documents and Handwriting Evidence [source]
- Forensic Document Examination: Principles And Practice [book]
- Scientific Examination Of Documents Methods And Techniques [book]
- Observations on paper as evidence [book]
- Forensic Document Examination: Fundamentals and Current Trends [book]