I don't know of any definitive studies but the general guidelines we have ascribed to have been that a body will not float unless water temps are at least 60 degrees.
Below that point decomposition and the development of gases related to bacterial action is not fast enough to cause the body to bloat, and consequently float, and using divers to search for and recover the body is going to be neccesary.
Depth also is a factor as increased depth means increased pressure which causes the gases developed through decomposition to compress, reducing the potential for the body to refloat. Essentially, you need a lot more decomposition to get the same amount of lift at depth
Around here with lakes to 150 ft deep and water temps at the bottom that never rise above the mid 40's, bodies just won't float. When they mention that "Superior never gives up her dead" in the "Wreck of the Edmond Fitzgerald" that is exactly what they are talking about. The 60 degree temp is not exactly research based but rather is based on historical observations of when and where bodies have and have not floated.
Body composition is another factor as adipose tissue is more bouyant than denser bone and muscle tissue and also tends to decompose at a faster rate creating more gas and more potential to refloat.
My understanding is that in warm water, large intact bodies from obese individuals can become very bouyant during decomposition and lift close to 300 lbs. I suspect most criminals probably under estimate the weight requirements by a large margin. A few cinder blocks is just not going to do the job for very long.
Also how much air is in the persons lungs makes a difference in how fast a person may initially sink. We had a slender teenage boy get hit by a jet ski and sink very quickly as the impact essentially deflated his lungs.
What you eat can also have an impact on if you float soon after drowning with some foods releasing more gas than others. How long it was since you ate also makes a difference as it relates to where the food is in the digestive tract.