Tag Archives: forensic ballistics

Firearms Analysis in New Orleans

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Firearm discharge

Cloud of particulates formed at firearm discharge to determine the distance a weapon was fired. Source: US Fish and Wildlife Service.

Last month, Bill Capo of New Orleans’ WWLTV posted a report on changes in that city’s police crime lab since Katrina. When Ronal Serpas assumed the position of crime lab superintendent, he found that the hurricane had destroyed the original lab, leaving a facility that barely functioned.

“This crime lab was basically dead on arrival,” Serpas told Bill Capo. “It was having very little success in doing firearms examinations. There was no real work going on with DNA.”

Serpas initiated a program to rebuild the lab with an emphasis on firearm identification to tackle the increasing number of violent crimes.

“It’s unbelievable the volume of work the firearms unit has done,” said Captain Michael Pfeiffer, the crime lab’s commander. “No place else in the country touches the volume of work this unit does. I can guarantee you, pound for pound, we are faster and better than anybody you want to look at.”

One outcome of the analysis is the finding that in many cases the same guns are used to commit multiple crimes. Investigators use the information to identify links between two or more crimes.

“There’s a small group of people out there committing a majority of the gun violence that occurs in the city of New Orleans,” Pfeiffer told Bill Capo, “and the more we can show the linkages between those people, and between the cases, the more likely we are to take, not just individuals, but groups off the street.”

If you plan to include forensic firearms analysis in your story, then watch the video of this report for insights into a real lab.

 

Tracking Firearms in Toronto

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CBC News report on firearm identification technology.

 

On May 13, CBC News posted an article entitled, “Bullets Decoded: Inside a Toronto Firearm Lab.” As detailed on the CBC News website, Toronto police use the Integrated Ballistics Identification System (IBIS) to analyze three-dimensional marks created on bullets and shell casings upon firing. The technology reveals links among crimes. In one case, for example, the same gun had been fired during two otherwise unrelated shootings and a bank robbery.

Developed by Montreal-based Forensic Technology, IBIS is used by Canadian and US police forces, as well as by other law enforcement agencies throughout the world. According to Robert Walsh, Forensic Technology’s CEO, IBIS has linked guns with more than 100,000 crimes in the United States alone.

IBIS’ success has not gone unnoticed by criminals. “I think the criminals have learned through the court system and word of mouth with each other that IBIS exists and it’s able to link up crimes to other crimes,” Toronto police detective Mike Grierson told CBC News. As a result, criminals sometimes “police their brass,” to avoid leaving evidence at a crime scene.

 

Forensic Firearms Identification

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Silver to bullets

Poster printed by Sir Joseph Causton & Sons, Ltd, London, 1915. Source: Library of Congress.

Forensic firearm examiners determine whether a certain weapon fired a bullet or cartridge found at a crime scene. Early efforts linked spent ammunition with a class of weapon. Following the 1862 shooting of Confederate General Stonewall Jackson, for example, investigators concluded that the General had been accidentally shot by his own side. The spherical projectile removed from the General had been fired from a smooth-bore musket, a type of weapon that the Union Army no longer used.

In 1912, Professor Victor Balthazard at the University of Paris formulated the basic principles of firearms examination. Using enlarged photographs, he compared marks created by a firearm on the surface of bullets and cartridge cases found at a crime scene with marks on ammunition that he had fired from a suspect weapon. In this way, he could connect crime scene ammunition to a particular firearm.

During the 1920s in New York, four men rediscovered Balthazard’s principles and initiated modern firearms identification: Charles E. Waite, Calvin Goddard, Philip O. Gravelle, and John E. Fisher. Gravelle had extensive experience with a comparison microscope to study fine details in cloth patterns. He suggested that they might be able to use the instrument to compare fired bullets and cases.

In a signal event of firearms identification, the group bought two comparison microscopes and modified them. They added a comparison bridge, and rotatable mounts for bullets and cartridge cases. Through the eyepiece of the bridge, two pieces of spent ammunition could be examined, one on each stage of the two microscopes.

Police departments and the courts became aware of the value of “fingerprinting” bullets, especially after Goddard testified about his findings in the 1929 St. Valentine’s Day Massacre. Within a decade, firearms identification became an established technique of criminal investigation.

GSR Speaks

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Gas precedes a fired bullet.

When a bullet leaves the muzzle, it is preceded by a gas bubble. Source: Alexander Jason, “Effect of Hair on the Deposition of Gunshot Residue,” Forensic Science Communications 6(2) (April 2004).

In a shooting, gunshot residue (GSR) can be found on the victim, on surfaces within a few feet of the sides of the firearm, and on the hands of the shooter. The excellent FirearmsId.com website offers a brief description of GSR generation:

When the firing pin of a firearm strikes the primer of a cartridge the primer compound ignites sending a flame into the cartridge case. Gunpowder in the cartridge case starts to burn, causing it to change from a solid material to a gas. This change creates pressure within the cartridge, which in turn forces the bullet down the barrel and down range. Pressure building behind the bullet is released when the bullet exits the muzzle of the firearm.

The bullet acts like the cork in a shook up Champagne bottle. When the bullet exits the muzzle, pressure behind it blows the gunshot residues out of the firearm’s barrel under high velocity. The residues are expelled from the barrel in a smoky cone shaped pattern.

Analysis of GSR can establish that a shooting took place and may link a person with that shooting. One day, GSR may reveal more details about a shooting. On June 18, 2012, University at Albany (New York) researchers announced that they developed a method to determine the caliber and type of weapon used in a crime by analyzing GSR. The technique uses spectroscopy with laser light. Lead researcher Igor Lednev cautioned that his team must continue their research before the method can be presented in a courtroom.