Some more info after I had the courage to go across the lake and look at her.
Something has ate her head off and ate only the guts out through both ends of her but there is no other damage to her body. What could have done this. We have alot of other ducks geese and another swan on our lake and nothing has eve been killed in this manner before.

i would think if it were a dog or coyote or other predator they would have plucked alot of feathers and ate the meat, but whatever did this only pulled the guts out from both ends and she was virtually un touched other than that. All the blood was gone and there was not a drop laying about. It is obvious from the trail neck feathers that it was pulled to the bank from the water and there are no large prints about but i did see 1 large claw type print in the mud.

we are in southeast indiana USA

Thanks for help !