The Importance of Ink in Forensic Handwriting Analysis

by Kevin Smith Author

In criminal cases, forensics play a crucial role in determining the facts surrounding a crime. The evidence is collected and analyzed by experts who conduct a variety of tests to recreate the crime and highlight important findings which are then used to either build a case or exonerate a defendant.

In forensic handwriting analysis, experts use a variety of examinations and laboratory equipment to inspect documents for forged signatures, alterations, page substitutions, or erasures. Additionally, the expert may be asked to examine a contested will or contractor determine authorship of a document. Ink type can provide important clues. Because the examination of the document is often tied to legal cases, it is important to contract the services of an established forensic handwriting expert in San Diego who has the background and resources needed to conduct an investigation.

Ink Analysis

In the investigation of questioned documents, ink analysis can provide crucial and compelling information in determining forged documents, checks, or wills, in addition to records alterations. To the human eye, many popularly used inks may look the same, but when examined under a microscope, even the slightest change in color may indicate an alteration, obliteration, or overwriting attempt.

Ink Analysis Using Light

Infrared or ultraviolet light can be used to scan the ink and determine the wavelengths of light different types of ink absorb using ultraviolet or infrared light. This process is called micro-spectrophotometry and does not damage the document. Each brand of ink offers its own true color and pattern, with some emitting light, and others disappearing under the same ultraviolet light. Another type of examination is conducted through infrared light, with a process called Raman spectroscopy. The high frequency of the infrared light causes the ink to become invisible, but if there are pencil or other markings underneath the ink, those will show up.

Liquid Chromatography

One method used to determine the chemical composition of inks used on a document is called liquid chromatography. A piece of the document is immersed in a solvent, dissolved, and then analyzed. It can then be compared to a U.S. Secret Service database containing nearly 10,000 different types of ink in production since the 1920s. In the 1990s, some manufacturers started to add chemical tags in their products that can provide clues to an ink’s production date.

It’s important to verify that the specialist is a board-certified and court-qualified forensic handwriting expert in San Diego.