It's my guess that deer was raised by people and eventually they let it go. I have a friend in MN who found a deer on the side of the road less than one day old. He raised it and would take it for walks on a harness. When it got big enough to release at 4-5 months old, it would still come back every day and would let my friend hand-feed it. He did gate it up during Deer season last fall, and released it for good after Deer Season.
He named the deer buckshot and would send me pictures of it from time to time. Below is a picture from Halloween with Buckshot dressed as a Deer Hunter.
I have videos of my kids playing with it and feeding it when it was a couple of months old.