January 04, 2011
This is the split-image view of a positive bullet match through a comparison microscope. The standard practice of the Dallas Crime Lab was to always place the evidence item on the left and the test-fired item on the right.
To most people, forensic bullet and cartridge-case matching means firing test shots from a suspect's gun and then using a special microscope to compare the markings to bullets or cases found in a victim or at a crime scene. The comparison microscope allows two bullets or cases to be mounted separately but viewed side by side through a split-image eyepiece. That makes up the bulk of the workload but wasn't always the most interesting of lab activities, at least not for me.
Interesting cases are challenging cases--ones where the investigating officers and lab people work closely to reconstruct a sequence of complex events that, hopefully, bring a suspect to trial. For me, the "no-gun cases" fell into the interesting category.
Connecting Random Cases
You don't need a multi-million dollar forensic facility to tell you cases are related if they happened over a few hours with a lot of witnesses. But what if the events are separated by weeks or months, cover several jurisdictions, and the only witnesses were murder victims? Good investigative methods, including centralized lab support, can tell detectives if events are related. If a firearm is used, the evidence it creates--fired bullets and cartridge cases--can help link events even before the firearm is recovered.
Because it persisted so long and affected several jurisdictions, a string of robbery-murders at little "mom and pop" grocery stores sticks in my mind. What we thought to be the first case had two dead victims and three .38 Special 158-grain lead RN bullets with Winchester's distinctive Lubaloy coating. The general pattern of rifling was clear--six lands and grooves with a left-hand twist. That made us about 99 percent certain that a Colt revolver had been used. This alone was unusual; as I wrote in a prior column, we found that criminals seldom showed good taste in firearms.
We could positively match two of the three bullets, showing they were from the same gun. The other had decent markings that suggested it was also from the same gun, but impact damage precluded our meeting the strict standards we imposed for labeling something a match.
Soon there were other robbery-murder cases in small grocery stores in the same area, and we ultimately had three more bullets just like the first. Again, damage prevented a conclusive match, but we could see enough to tell the officers that the cases were likely related.
The case broke when the bad guys used up their six Lubaloy loads and scored some M41 ball ammo in terrible shape. In yet another robbery, they aimed the gun at a storeowner's face and pulled the trigger; the cartridge failed to fire. The storeowner bolted down the canned food aisle, hurling cans of beans at the pursuing robber, who fired again. This time, the cartridge fired, but it was a squib. The low-velocity 130-grain FMJ bullet struck the clerk in the forehead and bounced off. It was enough to knock out the owner, but it saved his life.
The bad guys assumed the big red gash on his forehead was a lethal injury and resumed their ransacking of the checkout counter. When the clerk awoke, he had a whopping headache but a clear memory of what had happened. Using his description of the suspects' actions prior to the first attempt to shoot him ultimately broke open the case, but not before the deadly duo claimed more victims.
Two cartridge cases match on breechface marks. Machining marks on the pistol's breechface transferred to the primer cup at the time of firing.
During the months that this pair of thugs terrorized South Dallas, the lab was in daily contact with the detectives downtown. Some of us even rode shotgun with detectives as they searched for a vehicle that witnesses had associated with the murderous rampage. Between us, we had charted all the ammo and gun-type evidence, and we knew when the crooks ran out of one ammo type and when they changed guns.
After the arrests were made, bloodstain evidence let us include an even earlier murder that happened before the crooks got the Colt. In fact, we suspected the Colt was stolen from this first victim; other items belonging to this man--his watch and a portable radio--were eventually found in the suspects' possession. Connecting cases by guess is a waste of resources; for this one, we had scientific leads to keep the case active and ultimately bring the perps to trial. It also helped that one lab served many jurisdictions. If we connected a Dallas case with one in Grand Prairie, Texas, we contacted both agencies, so they could pool their resources.
No Gun, Just Bullets Or Cases
It's possible for a person to commit a crime and then successfully ditch the gun so it's never recovered. Then it takes more investigative work. About the time I started in the crime-fightin' business, a couple of high-profile, no-gun cases piqued my interest.
The evidence from the first was a dead body and a spent .38 S&W (not .38 Special) 146-grain lead bullet. A suspect was known to have an old break-top revolver that shot .38 S&W, but apparently, he had gotten rid of the gun after the offense. After weeks of investigation, a neighbor eventually remembered seeing the suspect stepping off his porch and firing a revolver into his flowerbed on the Fourth of July.
Shovels in hand, the crime-scene crew unearthed four lead bullets that were consistent with being from a .38 S&W. Although the damage from striking dirt was pretty bad, one bullet clearly matched the bullet from the suspect's dead friend. The jury liked the prosecution's case.
In another case, a man killed an acquaintance with a .30-06 rifle and then got rid of the gun. Park rangers remembered complaints days prior to the killing of someone "shooting a loud gun" too close to a campground; witnesses provided them a description of a truck that matched the murder suspect's. Detectives assigned to the murder case searched the woods and found a large tree with the remnants of a paper target and possible bullet holes in the tree trunk. They felled the tree and cut apart the section where bullets might be lodged, recovering several .30-caliber bullets. Two of them matched the bullet that killed the victim.
It's not always the bullet that yields critical information. Cartridge cases also contact uniquely machined gun parts and pick up mar
kings that can be positively associated to one firearm.
We worked a case from East Texas where a person was killed in what could be best described as a "drunken drive-by." A bunch of inebriates was riding in the back of a pickup truck, and one had a handgun that he fired randomly. One bullet struck and killed a man standing in his yard. The 9mm Luger bullet passed completely through the victim and was lost, but officers recovered a 9mm cartridge case from the street in front of the victim's house.
Plenty of folks had seen the truck and heard shots, so it was not hard to find it and its well-lubricated occupants. However, there was no gun in the truck. Fortunately, one person felt remorse after sobering up and came forward a day later. He said someone in the truck was shooting but could only narrow his suspicions to three people. Detectives spread out to learn as much about the three "possibles" as they could. Largely by chance, one person interviewed said he knew one of the three and that he was "an S.O.B." because he'd shot a hole in his den wall a few nights earlier. That immediately got the officers' undivided attention.
Matching extractor marks on two 9mm Luger cartridge cases definitively show that the two cartridges were fired from the same pistol.
The suspect had been at a party in this man's house and complained about a horsefly on the wall. He whipped a semiauto pistol from under his shirt and shot at the fly, leaving a bullet in the wall. Search warrant in hand, the crime-scene guys took apart the wall and found a 9mm bullet, but there was no autopsy bullet to compare this time. They asked the homeowner if he'd found a spent case. The owner said no, but that the room had not been cleaned since the party. (Nice!)
After about an hour of searching through empty beer cans and moldy pizza boxes, cops found a 9mm case in a magazine rack. Based on breechface marks transferred to the primer, we made a positive match to the case at the scene of the killing. The people at the party had no trouble identifying the fly-shooting drunkard, so the case was pretty tight after that.
Reloaders Get Involved
I was surprised when one of my buddies on the crime-scene search squad strolled in the office and said he'd dropped off a set of RCBS reloading dies with our evidence registrar, along with some reloads. He was working a burglary where a man's custom Browning Hi-Power was stolen. The victim was a reloader and said the pistol's magazine held handloads when it was stolen. Through other evidence, the police developed a suspect and executed a search warrant. They found no Hi-Power, but they did find a Hi-Power magazine full of reloads. It was the victim who suggested to the detective the idea of matching the cartridge cases to his reloading dies.
Being the "Reloading Dude," I was all over this case. I placed the cartridges from the magazine found in the suspect's house under the microscope and was a little dejected to find that the cases apparently had been resized several times in a steel die. All the overlapping scratch marks would be impossible to sort out. Then, while looking at the rest of the case surface, I saw several distinctive marks on the rim of the case caused by a firearm's extractor. The owner had provided some cases he'd saved for later reloading that he knew were fired in his Browning--it was the only 9mm he owned. I placed those under the other side of the 'scope and was rewarded with a view of identical extractor marks on the cases for the suspect and those from the victim. Faced with this, the suspect 'fessed up to this burglary and a number of others.
We faced a lot of challenges in our service to the justice system, but I will always have fond memories of our no-gun cases.
About the Photos...
The Dallas lab did not acquire a decent camera system for a comparison microscope until a month before I left in 1987, so I did not have quality photos showing bullet and cartridge-case matches. For this column, I called on good friends in the forensic business for help.
The photos used here are not from the cases discussed, as we had no way to photograph them at the time. They are presented here to help the reader visualize how examiners work with evidence. The digital microscopic photos in this article were kindly furnished by the Ventura County (California) Sheriff's Forensic Sciences Laboratory. I extend my sincere thanks to those hard-working folks in Ventura for helping illustrate this column.