Smiley Face Killers

The 6th and final episode of the season is on right now. I suspect before our story here ends, we will find the connection to this phenomenon.

Short story: Young, athletic males have been found dead in body of water weeks after they went missing from parties or nights out. All of them have very little deposition. All of the cases were marked as accidental drowning or undetermined. Evidence almost always points to them dying in another location and dumped in water. Most of them show different prescriptions in their bloodstream that would be used to sedate them. Some have bruising or ligature marks. None of them have water found in the lungs associated with drowning. None of them are mutilated or missing organs.

Obviously they are kept in containment for weeks between their disappearance and their discovery. What the fuck are these killers doing with them in the mean time? They aren't tortured in the physical sense.

The big question is are they being used for their blood? Adrenochrome? or some sort of hormone that the public isn't aware of yet?