Just for the sake of your story concept:
A large python could most definitely consume a small child. It would be more plausible for your story if somehow, let's say, that python was raiding a chicken coop or rabbit hutch on the farm for food. One day it came across the little girl tending her bunnies or gathering eggs. Maybe the little girl tried to defend her "pets" or maybe she just had the smell of these prey items heavily on her body, and the snake then killed and swallowed her. It would take a long time, surely more than an hour, for the python to engulf her.
Now. The python should have a place to hide in the immediate vicinity, because once it settled in to digest this large meal it would not be apt to move, or return to the farm as you put it. The hiding place needn't be very large - a meter square would be more than ample.
There would be two plausible reasons for this snake to regurgitate the child. One - the human was simply too large and as it began to be digested by gasses, the snake's body would become even more distended and it would then regurgitate it.
Another reason (and perhaps more suited to your story) would be for humans looking for the child to discover the large snake with the large lump. They began to beat the hapless serpent with tools, or throw rocks at it, causing it to regurgitate the meal. This is a common way for snakes, and some other animals who swallow large meals, to act when confronted with a threat when they are incapacitated by a gut full of food.
The condition of the body would depend on the time spent being digested as well as the ambient temperatures. The snake would be unlikely to regurgitate the prey item after more than a few days, I would think. The clothing should be relatively unaffected regardless of which end of the python it exits. And, of course, even if you allow the child to be digested in your story, that special ring or necklace she was given by her favorite aunt would be deposited in the, um, droppings, and found by your sleuth.
Hope that helps.
-Joan
p.s., Of course, in any of the scenarios above, the sadder but wiser (and still hungry) serpent lives to slip off unnoticed into the bush, never to prey on humans again.