Reference:
https://www.youtube.com/watch?v=s2Y-6UFV_jI
Above link to press meeting when Mrs. Dermond’s body found. A noteworthy statement is Sills responding to a question by a newsperson at 2’50” regarding why the body might have been found at that location, and in his response he used the words, “…or at least to that vicinity”. Just before the end of the meeting Sills is asked if the body could have floated to the location and his reply is, “I don’t think so…,” (because of the distance, he says) which seems to indicate it could have, but he just doesn’t think so, meaning it wasn’t tethered. He made no declarative statement that the body was not weighted, though unless the weight was so heavy no ordinary person could have managed it without difficulty, the corpse would still have risen though it would have taken additional time of decomposition to increase the corpse volume in order to lift the weight.
If Mrs. Dermond's body was in the water the night of Friday the 2nd, 14 days elapsed before the corpse was discovered. The lake was searched for those two weeks but was discovered by fishermen. It is certainly conceivable that the searchers simply missed seeing the corpse, which is somewhat embarrassing for them, but it may not yet have risen enough to be spotted as it was by the fishermen.
So it seems possible for the corpse to have been placed elsewhere, possibly far upstream, weighted. It also seems possible that the corpse was placed somewhere unknown in the lake at some time after the 2nd. The issue of weighted or not may depend more on the sharp eyes of searchers considering the possible circumstances.