Okay thanks. Mainly in my script, a cop gets into a shootout, and some bad things happen, and the wrong person gets killed, which drives the rest of the plot.
However, I do not want the forensics being able to trace the physical evidence back to the cop, and want the police to look for other possible suspects. So the cop would have to remove each of his fired bullets from the dead body as well as all the bullets in the walls and everything, before any police arrive to a 911 call, where gun shots are reported fired.
Since this crime was not planned, the cop has to make up for his mistakes that are already made in the crime scene, and that makes it tricky, compared to a pre-planned crime. I am not sure how to write it so that he can get away with it, while removing the ballistic evidence from the fired bullets, and dna. I can write it so that he wore gloves to the scene, in case something were to happen, that he was worried would be traced back to him, but that is a bit of a stretch.
Do cops often wear gloves, just in case they are worried about killing the wrong person, and do not want anything traced back to them?
One of the pillars of storytelling is authenticity. IS IT POSSIBLE that this person could really exist, or this event could really happen?
Suspension of belief.
The term suspension of disbelief or willing suspension of disbelief has been defined as a willingness to suspend one's critical faculties and believe the unbelievable; sacrifice of realism and logic for the sake of enjoyment
Your above scenario is just not believable, and I think there is zero chance he or she would get away with it. Maybe for one day, but that's it.
1. Removing the bullets from the body still leaves bullet holes. What's his plan to hide those? Is he going to tell the other police and forensics that's how he found the body?
2. Does he pack his own clips? If so, it is likey his prints are on each casing. He better find EVERY ONE of them. In a shoot out, people usually move around, hide behind a car, then a tree or building, then run and shoot to get ot the next place of cover. That is a lot of moving, with casings all over the place. He needs to retrace his every move - or did he stay in one spot and these guys just shot back and forth until one was finally hit? An innocent pedestrain distrcted by their phone walked right through the middle, and the cop filled them full of lead?
If someone else packs his clips, then their fingerprints will be on the casings. If they work in the police department, then that can probably be traced to them. Either way, the cop better find every single casing - and sort out the other guy's casings from his own, and have a good story in place as to why the other casing are there in the first place. Who was shooting at what?
3. Modern frensics can see a lot, including narrowing down a bullet type by the 'footprint' it leaves when it hits something, like a car. This cop not only needs to find all the spent lead (and the fragments) but also plug any holes left behind. He'll needs some bondo, various colors of car paint, cement filler, tire inflater, a tree bark repair kit, a window replacement kit, surgical instruments, and a trunk full of crime scene CYA goodies.
4. If this is a real shoot out, then who was the cop shooting at? Did the bad guy or gal (or whoever was shooting back) get away? If so, then there is a witness, who would likely want to make an anonomys tip against the cop. How the wrong person get in the way?
5. Powder residue on the cops hands.
6. Stray bullets can travel a long way. The cop needs to figure out how many bullets he fires, add up what he can find in the immediate area, then try and find any others unaccounted for. Could be ten blocks away, could be 30 blocks away. Either way, someone somewher my likely see or hear a bullet slam into a buildiing facade or a car or whatever, and maybe even report it.
7. If the cop has to crawl under cars to get to casings, he is going to look a little trashed when the other police show up. Does he have a good explanation ready to go?
8. You mention 20 minutes for a 911 response. This is possible and due to many factors, none of which are predictable. But, who made the call? Did they only hear the shots, or did they see something? And 20 minutes in NOT enough time to clean up the scene. He would likely assume he has 5-10 minutes before someone shows up. To his astonishment, he has 20. Where'a a cop when you need one?!
9. How did the cop end up here? A call came in? The shoot out just erupted out of the blue? Can he even see who is shooting at him? How does he know he shot the wrong person?
10. Cameras are EVERYWHERE. A local convenience store camera could have captured the cop's car passing in the direction of the shoot out at about the time of the event - maybe two or three cameras in various pocations captured the same cruiser - and the police department will want to know how and when the cop heard the shots, and why it took 30 minutes before he reported it (10 minutes for the shoot out, 20 minutes to clean it up). Or will he tell them he just rolled up on a body in the street, and that must be someone else's cruiser in the footage?
This especially is a ridiculous statement ...
Do cops often wear gloves, just in case they are worried about killing the wrong person, and do not want anything traced back to them?
You're asking us to believe your cop did all of this in 20 minutes ...
http://science.howstuffworks.com/csi.htm
I'd work on another idea. This one has too many holes, no pun intended.
Alex