Wait...Pipin and mehh, I get what you're saying, but it says four people touched the pills, including Shamrock.
I think I know who did this:Blue!
Here is why:
So, i've remembered from Whodunnit that anybody who got Scared isn't the killer.
Out of the four who touched the pills, I know that Blue was the only one out of the four who touched the pills and wasn't scared.
Here is what I think happened:
So, last night, Blue managed to do it again and kill somebody!
He decided to prepare for his third kill right away.
First, he stole some pills from the morgue, which he knew were long-lasting anesthesia pills.
He then told Shamrock to have some pills, as they would help him sleep better, which is what Blue said.
Obviously that was not true.
The next morning, Shamrock woke up VERY late and walked around clumsily while trying to get some clothes on.
After 45 minutes of trying, he finally got his clothes on and he went to the bathroom at 11:45 AM.
He was still tired, though.
He walked around delusionally, until Blue then came up behind him and cut off his head, amassing an amazing kill.
However, he had to hide the evidence.
He first dug up White's dead body, and along with Shamrock's disemboweled body, he buried the bodies in a another hole, and he spent about 15 minutes making it look like nothing had happened.
Then he got some extra soil from the hole to help him refill White's grave and make it look like someone had graverobbed.
Then he took the head and snuck it into a dish, just before everybody had come for lunch.
Once IR took the dish lid off and everybody ran, Blue ran behind everybody to hide the head.
He took the head and tossed it into a nearby pond, and he rushed back to his room, where he acted like nothing had happened.
That is how I think Blue killed Shamrock.
(Also, DAB for the best answer in Case 2!)