An inspection service analyst demonstrates the CrimeScope’s flexible lens while examining a questionable document.

Photograph courtesy of the United States Postal Inspection Service

The public relies on the Postal Service for safe, quick and reliable delivery of materials ranging from bill payments to birthday cards to merchandise. Advances in technology provide criminals with greater opportunity to commit postal crimes and make the work of the Inspection Service more crucial. While criminals look for new ways to circumvent the law, postal inspectors work hard to stay at least one step ahead of them. An important investigative tool is the forensic laboratory. Inspectors work with other investigators and forensic scientists, using use high-tech equipment to solve crimes committed through the mail.

This black box and attached flexible wand is a CrimeScope model CS-16-400. It uses different wavelengths of light to assist lab analysts to locate and identify trace evidence on a variety of sources. Light of different wavelengths can help analysts identify altered documents, and evidence from fibers to fingerprints that is invisible to the naked eye. The portable box can be carried to a crime scene if necessary.

On loan from the United States Postal Inspection Service

Image (right): CrimeScope model CS-16-400

A useful detection tool in the U.S. postal forensic lab is the ESDA, or Electro-Static Detection Apparatus. The machine detects indented impressions, such as handwriting, on paper. The ESDA reveals impressions too shallow to see without technical assistance.

A document is placed on the machine and covered by a thin layer of plastic film, which is held down by vacuum suction. The forensic document examiner deposits a negative electrical charge onto the imaging film with a hand-held corona wire. After the document has rested for a minute, the examiner pours glass beads with toner over the top. The toner sticks to areas of indentation, revealing impressions that had been invisible. As a final touch a sticky, transparent, plastic film is placed over the newly created traced item, preserving it for observation.

ESDA machine on loan from the United States Postal Inspection Service

Images courtesy of the United States Postal Inspection Service

Anthrax Reward poster

Less than a month after the terrorist attacks of September 11, 2001, the United States faced a new danger in the form of harmless-looking powder mailed to members of the media and two U.S. senators, Senator Tom Daschle of South Dakota and Senator Patrick Leahy of Vermont. The contaminated mail pieces killed five people and threatened a critical component of the nation’s communication infrastructure—the mail service.

At least two anthrax-tainted letters traveled through a large Washington, DC mailing center. When the letters passed through the automated sorting equipment, some anthrax spores were released into the facility. The contamination killed two postal workers, Thomas Morris, Jr. and Joseph Curseen, Jr. A task force that includes postal inspectors and FBI agents continues the investigation of this crime.

Photographs courtesy of the United States Postal Inspection Service, Dangerous Mail Investigations and Homeland Security Group