Koa Lorimer

Well, Nancy, this right here is a nine millimeter round.

The top part is the bullet.

And the back part is the casing.

Now, you can get DNA off this casing by fingerprints and sweat and whatever else they have on their hands when loading the weapon.

So this is how you load magazine right here.

And also, there are certain marks that are left on the casing after the round is fired.

Now, this is a pistol that this round can be fired from.

The bolt goes out the front and the casing is ejected out of the side.

Now, the firing pin leaves a mark on the back of the casing, which is unique to the weapon.

Then the extractor leaves scratches on the casing, which is also unique to the weapon, and the ejector leaves dents on the casing.

Now, all these marks can be traced straight back to the weapon it's fired from, and that could link the suspect to the gun.

It can also link the suspect to the casing based on the fingerprints they get off the casing itself.