Possum....tossum

I found a dead possum in the back yard this morning. I was hoping the critter had died of natural causes but as I picked it up to give it a decent burial ( I tossed it in the woods) I noticed a large gash across its throat and another a little lower down.  Why do animals kill? I can see if they need food but this was not the case.

I have said a few times that I would like to have cameras outside to see what happens during the night.
Maybe we're better off not knowing.