Full Answer Section

• Contextual Relevance: Elimination prints help establish context. For example, if a crime occurs at a construction site, fingerprints from construction workers, site managers, and even first responders who may have entered the scene are collected as elimination prints. This allows investigators to focus their search on prints that are not from these individuals, narrowing the suspect pool considerably.
• Protecting Individual Rights: Comparing an unknown print to elimination prints before a database search helps protect the privacy of individuals whose prints might be in the database for legitimate reasons. It prevents unnecessary scrutiny and potential bias.
• Ensuring Admissibility in Court: Judges are more likely to accept fingerprint evidence if it can be shown that proper procedures were followed, including the use of elimination prints to minimize the risk of error. Defense attorneys can and do challenge fingerprint evidence. A solid foundation of established protocols, including elimination prints, strengthens the prosecution’s case.

The Fingerprint Database: IAFIS/NGI

The primary fingerprint database in the United States is the Next Generation Identification (NGI) system, managed by the FBI. It’s the successor to the Integrated Automated Fingerprint Identification System (IAFIS). NGI contains fingerprints and other biometric data (like palm prints and iris scans) from various sources, including:

• Criminal records
• Civil applicants (for certain jobs or licenses)
• Military personnel
• Immigration records

While NGI is a powerful tool, it’s important to understand its limitations:

• Not Universal: It doesn’t contain fingerprints from every single person in the US.
• Search Parameters: Searches are typically based on specific criteria (e.g., a known suspect’s prints, prints found at a crime scene). It’s not a “fishing expedition.”
• Expert Analysis Required: Matching a print from the database is just the first step. A trained fingerprint examiner must then carefully compare the unknown print to the potential match to confirm its validity.

2. Your Construction Site Scenario: Fingerprint Issues

As the District Sergeant, you’ll face several challenges with fingerprints lifted from the construction sites:

• Numerous Individuals: Many people have access to the sites: construction workers, subcontractors, delivery drivers, inspectors, real estate agents, potential buyers, and possibly even trespassers. This creates a large pool of potential fingerprints and makes it crucial to collect elimination prints from everyone with legitimate access.
• Environmental Factors: Construction sites are exposed to the elements (dust, rain, wind), which can degrade latent prints, making them difficult to lift and analyze.
• Multiple Surfaces: Fingerprints can be left on various surfaces (wood, metal, plastic), each requiring different techniques for lifting and preserving the prints.
• Time Sensitivity: The longer it takes to process the crime scene and lift prints, the greater the chance of contamination or degradation.
• Chain of Custody: Maintaining a clear chain of custody for all evidence, including fingerprints, is vital for admissibility in court. Any break in this chain can cast doubt on the evidence.

3. Latent Prints in Historical Crimes

Latent prints have played a crucial role in solving numerous historical crimes, even decades after the event. Here are a few examples:

• The “Grim Sleeper” Case: For over 25 years, a serial killer terrorized Los Angeles. Latent prints recovered from crime scenes, combined with advancements in DNA technology, eventually linked Lonnie Franklin Jr. to the murders.
• The “Golden State Killer” Case: Joseph James DeAngelo Jr. committed a series of rapes, burglaries, and murders across California in the 1970s and 80s. Decades later, investigators used advanced DNA analysis of old evidence, along with genealogical databases, to identify and apprehend him. While not solely based on fingerprints, the re-examination of old evidence was crucial to this case.
• Cold Cases: In many cold cases, latent prints that were initially deemed insufficient or inconclusive can be re-examined using newer technologies and techniques. This has led to breakthroughs in cases that were once considered unsolvable.

The use of latent prints in historical crimes underscores the importance of proper evidence collection and preservation. Even if a print cannot be matched at the time, it may prove invaluable in the future as technology advances.