Discussion in 'Forensic Science' started by Forensics_Guy, Apr 11, 2007.
Were the firearms dusted fot fingerprints? Have the cartridge cases been compared?
Was there a unknown shooter?
That possibility has never been accounted for.
So there could have been an unknown hunter that also shot at the deer but hightailed it out of dodge when the game warden showed up... I'm kinda thinking outside the box.
Striations are toolmarks impressed on the projectile when it travels down the barrel. When a projectile breaks up, even into fragments, the striations do not dissappear, they are still present, if they were there to begin with.
There is no extra hunter/unseen hunter.
If you like, all three weapons were printed, and low and behold, the prints matched the person that was seen holding them. If asked in the future, DNA also matched. (I'm curious about the prints question - it's a standard jury/lawyer question - I mean if the guns were found in the persons hand, why dust for prints/DNA?)
There were no *found* casings at the scene.
Wait...were the warden and the 3 hunters tested for gun powder residue?
No, but here are the results:
All three tested positive for gunshot residue (GSR).
Please remember these results mean nothing because GSR testing only shows that someone has A) fired a firearm or B) handled a firearm or C) been in the vicinity of a firearm when it was discharged.
Gah, this thing is driving me bonkers. LOL! Okay, I forgot to edit my last post because i thought what i put was off the mark but anywho. How does one prove whose shot killed the deer between the two with the rifles?
The bullet fragments are consistent with a standard "snowstorm" pattern, which means that it was a high velocity bullet that brokeup once it hit the deer.
The recovered bullet weight of around 40 grains was a clue that the projectile was "small" in comparison to what a 30 caliber rifle would normally shoot. But it is a reasonable weight for recovered projectile fragments for a projectile the AR-15 would normally fire - 223 Remington or 5.56mm NATO.
But had the projectile been fired from the AR-15, we would expect SOME rifling marks on the recovered projectile fragments. It is this reason why the AR-15 is excluded as having fired the round that killed the deer.
The bow was already excluded since arrows do not "snowstorm" when they penetrate.
This leaves only the 30 caliber rifle as a possible choice. But how could the 30 caliber rifle fire such a light projectile with no rifling marks? The answer is a sabot round. Popular for obtaining extremely high velocities, and extremely flat trajectories. A sabot round is one that allows a projectile of smaller than normal diameter to be fired from a larger bored barrel, normally in a plastic cup. The plastic cup engages the rifling, gets the rifling marks impressed on it, but opens up and falls away shortly after leaving the barrel, launching a projectile at very high velocity, with no rifling marks.
Gosh, I just watched an episode of csi miami i think it was where callie talked about a bullet exactly like that. I should have paid closer attention. I do have alot to learn as far as ballistics goes.
Anyone interested in another Quiz?
I am, I enjoyed reading the theories of them even though I had no idea what was correct.
Count me in.
Count me in also. For the next 2 weeks, i'm not as busy anymore.
Ah yes a sabot! Used by snipers also, just like in the CSI Miami episode Kill Zone, season 1. A rubber casing encases the bullet, so striations only appear on the rubber case, but then it falls away. I was not aware that the bullet recovered from the deer had no marks. Then i would of known. (Damn. }
The White Powder
Case scenario - Officers have removed a small baggy containing a white powder substance. Due to the high flight risk of the individual the powder was removed from, it is imperative that a quick analysis is performed to determine if it is a controlled (contraband) substance.
There is insufficient time to perform gas chromatography, or prepare the sample for infra-red spectronomy.
What techniques/procedures would you use to identify the powder. Be specific as to techniques/chemicals used, and I will provide the observed results to such hypothetical tests.
Separate names with a comma.