That is interesting about the CCP. I think a lot of public institutions have been upgrading energy systems. A lot of these colleges are part of state universities, so might be part of system wide upgrades of heating/cooling systems.

Also, the R-22 as a knockout drug is very plausible. I wonder if that clears out fast enough that it doesn't show up in toxicology reports.

I am assuming that a toxicology report is done to determine if drugs or alcohol are present.

But I am mystified as to the actual means of death. If someone is clobbered over the head doesn't that show up in an autopsy. A hematoma? Yet most of these reports say no indication of foul play.