Its a long process but you start with the dog searching for treats along a track that u lay out. Eventually you switch to dragging liver, hides, blood and deer hooves. Then you start aging the tracks, starting with a few hours and working up to 24 hrs or more. Lots of practise 

 I have a red bone hound, he found a deer for me the other day and I’ve never trained him. He does chase deer on his own all the time 

Not sure if wasn’t just a fluke, we will see if I kill another that doesn’t drop immediately 

 Yes many dogs are totally capable of that. Its a bit different with a trained dog that knows exactly what they are doing and will detect and track aged tracks for long distances. If you want to know more I would check out john jeanenney. He's dead now but he has blog called born to track and good book on the topic. You may be able to find some podcasts or interviews with him.