Unvalidated Forensic Science

Toolmark Analysis and Compositional Analysis of Bullet Lead (CABL):
Toolmarks are the impressions that a firearm’s interior structure makes on the brass or lead of bullets that are fired from it.  Firearms examiners often testify that striations created by an individual gun are unique and that by analyzing marks on bullets found at a crime scene, one can trace those bullets to the gun(s) that fired them. However, a lack of statistical data hinders examiners’ ability to reliably trace ammunition back to a particular firearm.  The scientific community is currently unaware of the variabilities among different firearms’ toolmarks.  Consequently, there is no way to determine how many points of similarity are necessary to match a bullet to a gun, making toolmark analysis an inherently unreliable form of forensic science.


Comparative Bullet Lead Analysis (CBLA):
The scientific community has also recently called into question testimony relating to compositional analysis of bullet lead, or CABL.  CABL is a process by which forensic scientists compare the elemental components of bullet lead to determine if different bullets have a similar makeup. FBI agents have testified in CABL cases that two or more bullets originated from the same box of ammunition, or from another box of ammunition produced at the same place on or about the same date. The agents then used this testimony to link bullets found at the crime scene to bullets in a defendant’s possession.  

After a twelve-month study on CABL, the National Research Council published a report of their findings in 2004, titled Forensic Analysis: Weighing Bullet Lead Evidence.  The National Research Council concluded that:  “[t]he opinions in some cases indicate that prosecutors and courts have overstated the probative impact of [CABL bullet] matching evidence,”Based on the Council’s findings, the FBI discontinued its practice of providing CABL testimony in 2005. Nonetheless, many of those convicted based on CABL evidence remain imprisoned.


Arson Science:
Over the past decade, fire investigation techniques that have been used for over forty years have been cast into serious doubt.  This has provided a new avenue for challenging wrongful convictions.

A primary goal of arson investigation is to ascertain whether accelerant was used to create the fire.  Arson investigators then testify that the use of accelerant shows intentional human action, as opposed to accidental, electrical, or natural causation.  Despite initial heated debate as to its conclusions, the National Fire Protection Association’s arson and fire investigation guide, NFPA 921, is now treated as the authoritative source on proper accelerant detection procedures. NFPA 921 outlines investigation best practices and disbands many of the myths that have formed the basis of arson investigation for decades. 

Case Study: Victor Rosario

On March 15th of 1982, a fire consumed a three story building in Lowell, Massachusetts. Eight people lost their lives while bystanders desperately looked for ways to help. One of these individuals was 24-year-old Victor Rosario. In the midst of the tragedy, Rosario broke a window of the building in attempt to help, but the fire was so strong that it knocked him back. Despite being an innocent bystander, Rosario was arrested and eventually convicted of arson and eight murders; he was sentenced to life in prison. Investigations by the police into the cause of the fire made up the majority of the evidence against Rosario, but were fundamentally flawed. Years after his conviction, the New England Center for Investigative Reporting began an investigation into the original findings. Their investigation found egregious flaws in the methods and conclusions that convicted Rosario. Among these discrepancies were findings that the police assumed from the start that the fire was arson, burn patterns that could not have conclusively been caused by arson, and no accelerants, bottle glass, or other physical evidence of the three Molotov cocktails was discovered at the scene. On July 7, 2014, a Superior Court judge voided the conviction and ordered a new trial. Victor was released after 32 years.


Although fingerprint evidence has long been considered a reliable way of identifying criminals, the infallibility of this forensic science method has recently been called into question.  Crime scene investigators use partial latent fingerprints found at a crime scene to identify potential suspects.  Yet recent studies have shown that fingerprint analysis is not as accurate as once thought. Although the scientific community does not doubt that each person’s fingerprints are unique, questions have been raised as to whether partial fingerprints can be considered a match to fingerprints made when one’s fingers are placed flat to make an inkprint. The impression left by a finger differs each time it comes into contact with a surface based on the angle of the finger, the amount of pressure the finger exerts on the surface, and how much of the finger is captured in the impression. Thus, even though fingerprints are unique, due to distortions in prints taken from a crime scene, prints from two different people may be confused, and impressions made by the same finger may not look similar enough for an examiner to identify them as coming from the same source.

This problem is exacerbated by the lack of standards for fingerprint examiners and the subjectivity involved in fingerprint analysis.  Many agencies that conduct fingerprint analysis do not require that latent print examiners be certified.  This is particularly problematic since the results of fingerprint analysis are largely a product of human interpretation.  There are no particular measurements or standard test protocols for fingerprint analysis. This means that a fingerprint examination is not necessarily consistent from examiner to examiner, and studies show that even an analysis made by the same examiner may not be the same when repeated at a later time in a different context.


Case Study: Terry Patterson
In 2005, NEIP filed an amicus brief in the case of Commonwealth v. Patterson, challenging the fingerprint testimony that was used to convict the defendant. Patterson was convicted in 1995 for the murder of Boston Police Detective John Milligan. Patterson’s conviction was vacated in 2000 based on ineffective assistance of counsel, and before retrial, Patterson moved to exclude the fingerprint analysis testimony on which his conviction was based. At trial, a member of the Boston Police Department had testified that four fingerprints found on the window of the truck in which the police detective was shot matched Patterson’s fingerprints. This witness explained that although the fingerprints could not be linked to Patterson when considered individually, when considered as a whole, they were a match to fingerprints from one of Patterson’s hands.

The Massachusetts Supreme Judicial Court held that analysis related to fingerprints that have been grouped together for examination, known as “simultaneous impressions,” does not meet the reliability standards set forth in Daubert and Lanigan. The court stated that the theory and methodology of latent fingerprint identification cannot be “applied reliably to simultaneous impressions not capable of being individually matched to any of the fingers that supposedly made them.” Read NEIP’s amicus brief for Patterson


Microscopic Hair Comparison

For decades, the FBI Crime Lab has conducted hair microscopy, where an examiner uses a high powered microscope to view hair from a crime scene and compare it to a known hair sample.  Looking for similarities in each hair, if enough characteristics are the same, the examiner deems the hair a “match”.   

Scientists have criticized this forensic discipline and noted its limited reliability based, in part, on the unknown pool of subjects with the same hair characteristics.  In the late 1990s, and the use of mitochondrial DNA testing, the FBI crime lab limited its use of hair microscopy and used it only in conjunction with DNA testing to confirm results.    

Following a trio of DNA exonerations in Washington DC (from 2009-2012), it was discovered that all three defendants were convicted on FBI microscopic hair comparison evidence which turned out to be wrong. The FBI then began an internal review of microscopic hair analysis cases to determine the extent to which flawed evidence may have tainted convictions. The FBI estimates that approximately 21,000 cases involved microscopic hair analysis.  In July of 2012, the Department of Justice publicly announced a historic review of all cases with hair microscopy evidence in collaboration with the Innocence Project and NACDL.