Newswise — A document, even one created by persons determined to remain unknown, can reveal more than its authors intended. The ink used to write a document can tell investigators a great deal about the document’s origin.

Inks in one form or another have been around for at least 5,000 years. Scientists can analyze an ink’s components and determine when it was first manufactured, its brand, its composition, and other information by comparing the analysis results to the more than 10,000 inks and matching analyses stored in the International Ink Library managed by the U.S. Secret Service. State and local police contact the Secret Service and request the library’s assistance when they are investigating suspicious documents.

Until recently, Secret Service investigators could spend hours flipping through hard copy pages in the International Ink Library’s analyzed samples to identify an ink. To speed up the painstaking process and ensure its continued accuracy, the Secret Service and the Department of Homeland Security (DHS) Science and Technology Directorate (S&T) teamed up to support the development of a library that has these materials in electronic form, resulting in the Digital Ink Library. Formally launched in 2009, the Digital Ink Library is a searchable database containing the electronic version of the International Ink Library’s collection. Using this resource, the Secret Service Forensic Services Division can quickly identify the most likely matches, even if the ink being researched comes from a common blue or black ballpoint pen.

“With this digitized search system, search times through the repository are reduced to minutes, resulting in a list of potential candidates available for comparison,” said Robert Ramotowski, chief research scientist with the Secret Service Forensic Services Division.

To analyze an ink sample, forensic scientists separate its components using planar thin layer chromatography. This process uses solvents to separate the ink into bands of color on a page. Each ink creates its own color bands, thus forming a “fingerprint.” Scientists compare the unknown sample’s bands to known samples to find a match. The International Ink Library kept pages of analyzed samples in binders, but some details faded from the paper over time. The deterioration made it challenging to match samples in some instances, according to Shane Cullen, program manager in the Reconnaissance, Surveillance, and Investigative Technologies program area at the DHS S&T Command, Control, and Interoperability Division (CCI), which supported the development of the digital library.

“It took a lot of experience and training to know what dye components might have degraded from the known samples in the library,” Cullen said. The software automatically selects the known samples that most closely match the ink of interest. To create the database, each vial of ink in the International Ink Library had to be analyzed using chromatography, and the results uploaded to the digital library. CAMAG Scientific, Inc. analyzed more than 8,500 ink samples and digitized them for use in the database. The Institute of Forensic Science of the University of Lausanne (UNIL) in Switzerland designed and built the digital library based on the work of consultant Dr. Cedric Neumann, who accepted a position as a professor at Pennsylvania State University in 2010. The Digital Ink Library includes an advanced quality assurance system to ensure each sample entered into the system has been analyzed correctly and is properly tagged and tracked, according to Neumann. The main computer scientist on the project, Thibault Genessay from UNIL, also implemented an electronic case file and lab management system in which ink examiners can take notes. Users can work on several cases simultaneously using the software’s features.

“The e-case system renders the overall examination more transparent and allows [users] to search and retrieve case archives, which is useful when there is a need to go to court several years after the actual processing of evidence,” Neumann said.

More than half of the International Ink Library’s work involves analyzing ink samples for international, federal, state, and local law enforcement investigations, according to Cullen. Anyone who needs assistance analyzing ink from pens or printers for a criminal investigation can contact the nearest local Secret Service field office. (A complete list of field offices is available at )

The International Ink Library has helped investigate forged documents, threats against government officials, suspected terrorism, child pornography, medical fraud, war crimes, and obstruction of justice cases, according to the Secret Service.

The ink library is primarily used to determine a document’s authenticity, according to Ramotowski. Secret Service researchers test an ink to determine whether it was available at the time the document was supposedly written. If the ink was not manufactured until after that date, investigators consider the document fraudulent. The International Ink Library’s collection includes samples that date back to the 1920s.

Investigations can proceed faster with the digital database system in place. “This is a quantum leap forward for the field of forensic question documents,” Cullen said.

The Digital Ink Library currently includes approximately 9,000 inks, many of which are rare and irreplaceable. For more information, visit or

(This story first appeared in the R-Tech Newsletter at This link also provides access to past issues of the newsletter, as well as the opportunity to subscribe to future issues. The newsletter is part of the Department of Homeland Security Science and Technology Directorate’s First Responder Technologies (R-Tech) outreach program to federal, tribal, state, and local first responders. R-Tech’s mission is to protect America against terrorism, disasters, and all other hazards by providing first responder solutions for high priority capability gaps due to technology and assisting first responders through rapid prototyping, technical assistance and information sharing.)

Register for reporter access to contact details