That would be my guess, dancinunderthemoon.. Chances of her emerging from 46' depths of the lake floor would be doubtful, imo, due to the weight of the cinder blocks combined with the rope/s, clothing, or body becoming entangled on the tree limbs.
We worked a lot of accidental drownings on the Chattahoochee River in Atlanta.. Most times they would get entangled on fallen tree limbs and float up becoming visible after about ten days, depending on the time of year/water temperature. Wondering what the lengths of the anchor ropes were? A lot of info about the perp/s can be determined by the type of rope, as well as the knot/s used.
Imo, due to Mrs D's body size, the 60# of weight alone would have been sufficient to keep her body submerged...
The info of the multiple blows and that a hammer like object was used is also very interesting, imo. This signature aspect of these soulless savage/s are a unique and integral part of their deviant behavior and indicates their viciousness and intent on causing the victim unnecessary/needless severe pain, imo..
___________
<off topic sort of>
The Apalachee River is one of the two rivers that feed Lake Oconee.. This caught my interest for several reasons.. History, specifically native american/mound dwellers history is a hobby of mine. Many of the Islands on Lake Oconee are indian mounds. It is very possible, and even likely, imo, that the trees where Mrs D was located grew from an Apalachee Indian Mound.. The Appalachian Mountains, thought to be the oldest mountains in the world are named after the Apalachee Indians; today called the East Missippians, who are now based in Louisianna..
That is very interesting about the mounds and apalachee indians. Funny, yesterday, I was thinking about coves and how they are formed due to the layout of the land once the river is dammed, it's basically just land on the shore that was just a little lower than the shore around it, allowing it to flood, so it stands to reason that there could be various land levels under the water, I"m sure in the 50's no one put up a fight over an indian mound like they would (and rightfully should), today, Im not familiar with their size but if they were right along the rivers edge, could be
Ok, so allow me to start with these images.......


Could we entertain the thought, since we are pretty certain a boat was used in this crime, that she was hit with a boat anchor with sharp points and ski rope or boat tie down rope was used to anchor her? Pontoon boats do pull skiers and tubers if the engine is big enough, as well as v hull type boats which is more the norm for skiers
Just making assessments on the types of rope
I do not know what other uses there is for rope. I'm sure there are many but the only thing we use rope for is our boats
We use various types of robe, but a certain kind for tubing and skiing, so there's a clue I guess, if we knew the type rope
Also, a smaller rope is used for many sailboats
Another thought is that if you tie the rope around a solid cinder block like a package ribbon, it would hold I would imagine but maybe not a ski rope, they are slicker BUT they do not expand and stretch when wet and movement, like the cotton/cloth types do, sorry, not familiar with what ropes are made of
I am guessing the blocks were still attached, since there was a description given