wow... thats a bunch of really bad things.... first question first.... that family friend, did he survive? will he make it? "gunned down by police" sounds bad.

about the smell in the car... other than finding the source and removing it, i think you cannot do much, and it will take ages until it goes away.

i have one weird idea that may help with the car smell problem.... maybe try these dermestid corpse-eating beetles. you could introduce them into the car. if they can deal with it, they will eat it up, leaving behind a skeleton, a bunch of dead beetles, and no smell. and if the conditions are not right, well, you just have to vacuum up a few dead beetles. but no, it probarbly wont work, because the beetles seem to be hard to get and they also need water and when there is too much rot going on they may have trouble getting the job done. in the right conditions they could clean a snake, or any other small dead animal, down to the bones in just a few days, scientists and taxidermists use them to obtain perfectly white skeletons and bones. but they are too expensive and i have no clue if they would survive in the car and if enough of them would reach the snake.

i guess you really need to find and remove the source of the smell.