Law enforcement television and courtroom fingerprinting have created the perception that fingerprinting can be done correctly. Although the patterns of each finger are made in the womb and can be seen on the skin, it is important not to assume absolute certainty.
Looking at the Numbers
Famously, the FBI estimates that fingerprint identification is 99.8% accurate. This accuracy is very comforting when dealing with a burglary or murder case that has a limited number of suspects. This is less inspiring when you consider the millions of people who are alive today and the computer databases that can search through thousands upon thousands of arrest records. We often refer to snowflakes and fingerprints as examples of uniqueness in our conversations. However, even this snowflake cliché has its limits. A researcher can catalogue enough snowflake patterns and eventually find snowflakes that can be distinguished even at that magnification. Practically speaking, there are only so many variations of whorled lines or geometrical flakes. The subtle variations become challenging to see after a certain point.
Television shows frequently proclaim, “It’s an equal match!” Or something comparable to specific. The television audience gets bored when you say “possible match”. “Why can’t these analysts just say we have the bad guy with plain language?” It is rare that evidence matching suspects can be proven beyond a reasonable doubt. Even eyewitnesses may be wrong in identifying a suspect or describing it. The evidence of fingerprinting at a crime scene is often incomplete or smudged. Few criminals will dip their fingers in ink, then roll each digit with a firm rolling pin immediately after the crime. Investigators look for evidence on glass and other hard surfaces. You might find several sets of prints in a public area like a hotel room.
Databases and Forensics
Although the term “forensics” is often associated with detectives and courtrooms, it can also be used for argumentation and debate. Anything that is considered forensic should be debated. Although fingerprinting can be a powerful tool to narrow down suspects and add other evidence to the case, jurors and the public should be cautious about issues that rely almost exclusively on this type of evidence. A 0.2 per cent failure rate is unacceptable when you consider how many potential matches are stored in national databases such as America’s Integrated Automated Fingerprint Identification System. The FBI uses IAFIS. It contains more than 70 million sets. This database includes more than prints that were taken at local police stations during bookings. This database also includes groups that have been submitted to background checks. The FBI adds these sets to the same criminal record database when an employer offers prints of job applicants.
Employers still find fingerprinting a practical way to complement other background checks. Everyone needs to be aware of the possibility of errors when too much relies on one form of forensic evidence.