Forensic science — FBI Bullet-Lead Technique Dead Wrong
“For over thirty years, FBI experts testified about comparative bullet lead analysis (CBLA), a technique that was first used in the investigation into President Kennedy’s assassination. CBLA compares trace chemicals found in bullets at crime scenes with ammunition found in the possession of a suspect. (…) Although the FBI eventually ceased using CBLA, the Bureau’s conduct in first employing the technique and then defending it after it was challenged provides an insight into how forensic science sometimes works.”
Paul C. Giannelli
“We cannot afford to be misleading to a jury. We plan to discourage prosecutors from using our previous results in future prosecutions.”
Letter from Dwight E. Adams — then FBI lab Director — to FBI Director Robert S. Mueller III
Since the 1960s, testimony by representatives of the Federal Bureau of Investigation in thousands of criminal cases has relied on evidence from Compositional Analysis of Bullet Lead (CABL), a forensic technique that compares the elemental composition of bullets found at a crime scene to the elemental composition of bullets found in a suspect’s possession. Different from ballistics techniques that compare striations on the barrel of a gun to those on a recovered bullet, CABL is used when no gun is recovered or when bullets are too small or mangled to observe striations. Follow us on Twitter: @Intel_Today
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A True Story — In 1995, former Baltimore police Sgt. James A. Kulbicki was convicted of first-degree murder. The prosecutor convinced the jury that, in 1993, Kulbicki had killed his mistress — 22-year-old Gina Nueslein– with his off duty .38-caliber revolver.
The scientific evidence was “irrefutable”. The bullets recovered from the victim’s body and from the crime scene had been fired by his gun.
“I wonder what it felt like, Mr. Kulbicki, to have taken this gun, pressed it to the skull of that young woman and pulled the trigger, that cold steel,” the prosecutor asked rhetorically during closing arguments.
Forensic Science — In order to move along a stable straight trajectory, a bullet must spin on itself. To achieve such spin, spiralling “grooves” are machined in the inside of the weapon barrel.
The size of these “grooves” as well as the “lands”, the angle of the grooves, their number per length and the direction of rotation — clockwise or anticlockwise — generally permit to identify a type of weapon. For instance, Colt traditionally uses a left-hand twist while Smith & Wesson uses a right hand twist.
Moreover, specific imperfections of a barrel may allow in some case to match one bullet to a particular weapon. In the best-case scenario, two bullets fired by the same gun will not look alike but they are likely to show areas of resemblance.
When such test is not conclusive or not possible — because the bullets fragments are too small or because the gun is not recovered — it is still possible to analyze the lead content of the fragments and compare it to bullets known to belong to a suspect.
The Scientific Evidence Against Kulbicki
Maryland’s top firearms expert told the jury that the size of the bullet was compatible with Kulbicki’s gun and that he had cleaned the gun.
He added that he had not been able to identify the marks from the barrel.
Last, he testified that the lead content of the bullet that killed his mistress was identical to the content of bullets from a box belonging to Kulbicki.
“Out of the billions of bullets in the world, is this just a coincidence that this bullet ended up in the defendant’s off-duty weapon,” a prosecutor asked.
A prosecutor told the Jury that the evidence presented by the forensic experts was “a significant piece of evidence” and a “major link” to establish Kulbicki’s guilt.
The jurors agreed. Kulbicki was sentenced to life in prison without the possibility of parole.
Joseph Kopera, one of the forensic experts who testified at the trial, presented the formal reports to the defense.
But his working notes were not given to them either at the trial, or at the appeal, which Kulbicki lost.
These notes conflict with the report on all grounds.
Kopera testified that the fragments were consistent with a large-caliber, probably a .38.
His notes tell that the first fragment came from a medium caliber and that the origin of the second fragment could not be determined.
Kopera testified that the gun had been cleaned. His notes read, “Residue in barrel: Yes. Bore condition: Dirty.”
Kopera testified that he could not identify the grooves and lands on the fragments. His notes reveal that the fragment’s land width was 0.072 inches and its groove width was 0.083 inches.
Bullets fired from Kulbicki’s Smith & Wesson revolver had a land width of 0.100 inches and a groove width of 0.113 inches.
The difference is significant enough to state beyond doubts that Kulbicki’s gun did not fire the bullet that killed his mistress.
Kopera testified that he could not identify the twist. His notes indicate that he had detected a “slight left twist” while Kulbicki’s off-duty weapon makes right-twist markings.
Kopera testified that the lead content of the bullets were identical. It was not.
The amount of arsenic in the fragments significantly differed from the one contained in the bullets belonging to Kulbicki.
No Degree — At the trial, Kopera testified that he had an engineering degree from the Rochester Institute of Technology and a mechanical engineering degree from the University of Maryland. Neither institution has ever heard of him.
A Widely Used Technique
“Every critical part of Kopera’s testimony was false, misleading, based on improper assumptions or ignored exculpatory information,” Suzanne K. Drouet, a former Justice Department lawyer, told the judge in her recent motion seeking a new trial for Kulbicki.
“If this could happen to my client, who was a cop who worked within this justice system, what does it say about defendants who know far less about the process and may have far fewer resources to uncover evidence of their innocence that may have been withheld by the prosecution or their scientific experts?”
Following a 2004 National Academy of Sciences report that sharply criticized the FBI’s bullet-lead technique, the agency no longer relies on this method.
After retiring from the firearms section of the Maryland State Police, Kopera committed suicide.
For more than 30 years, his expertise has helped secure countless convictions.
Nationwide, it has been estimated that the method has been used in more than 2,000 cases over four decades.
Several former FBI employees believe that a review of all cases where the CBLA method was used in testimony should be urgently conducted.
“It troubles me that anyone would be in prison for any reason that wasn’t justified. And that’s why these reviews should be done in order to determine whether or not our testimony led to the conviction of a wrongly accused individual,” said Adams, the former FBI lab director.
The second in command agree.
“I don’t believe that we can testify about how many bullets may have come from the same melt and our estimate may be totally misleading,” declared deputy lab director Marc LeBeau in a May 12, 2005, e-mail.
So far, the FBI has rejected such reviews on the basis that it would be very expensive. A sum of US$70,000 was mentioned.
Since 2005, the nonpartisan Forensic Justice Project, run by former FBI lab whistle-blower Frederic Whitehurst, has tried to force the bureau to release a list of bullet-lead cases under the Freedom of Information Act.
In academic circles, some experts have not hidden their anger toward the program and what seems to be an attempt to cover-up decades of fraudulent forensic sciences.
Clifford Spiegelman is a statistician at Texas A&M University. He reviewed the FBI’s statistical methods for the science academy.
“They said the FBI agents who went after Al Capone were the untouchables, and I say the FBI experts who gave this bullet-lead testimony are the unbelievables.”
Several lessons can be gleaned from the CBLA experience. In the conclusion of his excellent paper on the subject, Paul Giannelli wrote:
First, the failure to publish the empirical data that supports scientific conclusions is unacceptable. Scientists “are generally expected to exchange research data as well as unique research materials that are essential to the replication or extension of reported findings.”
Second, defense attorneys were unable to successfully challenge the evidence until William Tobin, the retired FBI expert, became a defense witness. This is not surprising because no defendant, no matter how rich, can conduct extensive empirical studies. A defense expert in a particular case can critique the bases of a prosecution expert’s opinion but can rarely replicate the research upon which that opinion rests.
Forensic Science: Last Week Tonight with John Oliver (HBO)
Forensic science used in criminal trials can be surprisingly unscientific. Maybe a new television procedural could help change the public perception.
Comparative Bullet lead Analysis: A Retrospective — Paul C. Giannelli
Comparative bullet-lead analysis – Wikipedia
“For over thirty years, FBI experts testified about comparative bullet lead analysis (CBLA), a technique that was first used in the investigation into President Kennedy’s assassination. CBLA compares trace chemicals found in bullets at crime scenes with ammunition found in the possession of a suspect. (…) Although the FBI eventually ceased using CBLA, the Bureau’s […]
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